# Solution to the rear O2 CEL (P0420)



## kdub790 (May 27, 2003)

Finally... it has arrived!
*Non-permanent mechanical solution to the rear O2 CEL (P0420)*

*CEL free for 12,000 miles and counting! (as of 5/23/05)*
First of all, let me thank our scooby friends for the idea:
http://forums.nasioc.com/forum...l+fix
Basically, this is a solution to the dreaded _CATALYST EFFICIENCY BELOW THRESHOLD CEL (P0420, DTC 16804)_ that many of us get from upgrading the downpipe. The idea is to place a gap between the pipe and the sensor to reduce the amount of exhaust gases that the sensor will see/detect. This becoming a very popular mod over on the Impreza boards since it is NON-PERMANENT, and it does not require modification to the O2 sensor harness. Normally, I would throw a CEL about every 85 miles, so far this mod has been worthwhile.
*Parts/tools Required:*
1)	Help! Part no. 42002 and/or 42009 by Motormite, these are known as sparkplug-arresters, which should be available at any generic auto supply store (e.g. Pepboys, Autozone, etc.). Should run about $5 per package.
2)	Tools
-	means to lift/secure vehicle
-	10 mm socket or wrench
-	7/8” wrench for O2 sensor (or 22 mm)
-	drill and 1/2” drill bit (read below) 
-	Dremel tool and various bits
-	zip ties & *****
3)







(most defly)
*Procedure:*
1)	Jack up car and secure with jack stands.
2)	Remove 2 plastic nuts and shield covering the O2 sensor/harness junction (10mm), this will make the R&R of the rear O2 much easier.
3)	Remove the rear O2 sensor, which is the one downstream of the cat (7/8” or 22mm).
4)	Modify the sparkplug-arrester(s). A 1/2” drill bit did the job for the Scooby sensor, but the vdub sensors are setup differently. 
First I drilled out the arrester using the 1/2” drill bit, then I used various drill bits and the Dremel to shave the rest until the sensor would fit. If you have the means to measure the sensor and get the appropriate drill bit, that would be highly recommended.
5)	Install arrester(s) into downpipe & replace O2 sensor (7/8” or 22mm).
From the pictures you can see that there are several combinations for the fix. The 42002 is a tapered-mount and the 42009 is a flat-mount with a crush washer. The 42002 (tapered) is notably longer in length than the 42009 (flat).
I elected to start off with the 42002 (tapered) only, which is the longer of the two, this worked out fine for 120 miles. Next, I placed a non-drilled 42009 (flat) in front of the 42002, so far no problems. 
Another method for using two arresters in-line is only drill through both. Some Impreza owners have seen a _SLOW RESPONDING O2 SENSOR CEL (P0139, DTC 16523) CEL_. As you can see there may be some trial and error to find what’s right for your dub (specifically the cat or lack of in your downpipe).

6)	Replace 2 plastic nuts and shield covering the O2 sensor/harness junction (10mm).
7)	Secure harnesses with zip ties.
8)	Clear DTC’s/Reset ECU. 
That’s all folks! http://****************.com/smile/emthup.gif

Help parts








Help parts again








42009 drilled








42002 only








42002 (drilled) & 42009









[******]As always *YOU* assume all responsibility for this mod![/size]



_Modified by kdub790 at 3:52 PM 5-23-2005_


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## jeller (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

Looks good, hope it works for ya. Question if it affects any of the information the O2 sends to the ecu? Im gonna try this, I cant stand that cel anymore







good write up http://****************.com/smile/emthup.gif 


_Modified by jeller at 10:28 AM 4-29-2004_


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (jeller)*


_Quote, originally posted by *jeller* »_
Question if it affects any of the information the O2 sends to the ecu?

that is the point to doing this mod. basically the rear O2 sensor functions as a tattle-tail for whether the catalyst is working like the ecu thinks it should.
perhaps this little write up will shed some light on the function of front and rear O2 sensors.
click-me.


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## Ken1.8T (Feb 16, 2001)

*Re: Solution to the rear O2 CEL (kdub790)*

This is an awesome mod, I can not wait to give it a try! Thank you!


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## jeller (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*


_Quote, originally posted by *kdub790* »_
that is the point to doing this mod. basically the rear O2 sensor functions as a tattle-tail for whether the catalyst is working like the ecu thinks it should.
perhaps this little write up will shed some light on the function of front and rear O2 sensors.
click-me.

Thanks for the link on the O2 sensors, innformative, what I meant was will it affect it in any negative way? But now I understand it better http://****************.com/smile/emthup.gif


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## VDUBNDizzy (Mar 12, 2003)

*Re: Solution to the rear O2 CEL (kdub790)*

Interesting. My guess is the metal in the "spark plug arrestor " works as a heat sink around the o2 sensor, keeping it happy.


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (VDUBNDizzy)*


_Quote, originally posted by *VDUBNDizzy* »_Interesting. My guess is the metal in the "spark plug arrestor " works as a heat sink around the o2 sensor, keeping it happy.

exhaust gases still reach the sensor, just not as much as before.


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## VDUBNDizzy (Mar 12, 2003)

*Re: Solution to the rear O2 CEL (kdub790)*

But you're implying that less heat will keep the code from popping. But it's the opposite that should be true.


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## Power5 (Jun 19, 2001)

*Re: Solution to the rear O2 CEL (VDUBNDizzy)*

do you know what the output change is? I use that for my A/F gauge at the moment, so if this kills its accuracy, I dont want to do it. Just wondering.


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## slugII (Apr 5, 2002)

*Re: Solution to the rear O2 CEL (VDUBNDizzy)*

A heat sink would reduce the temp of the sensor which would not help.
I think all it's doing is moving the sensor further away from the exhaust stream. Thereby reuducing the concentration of pollutants being sensed by the sensor. 
So the sensor is perceiving a cleaner exhaust just because it is moved further away.
The trick is to get the right level of exhaust on that sensor because too little heat will throw a code. That's why you have to play with the fitment distance with multiple pieces to get the correct result.
If this works, it leads me to believe that the cause of this code is not so much the temp of the sensor but, actual catalytic converters that aren't doing their job scrubbing the exhauts.


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## VDUBNDizzy (Mar 12, 2003)

*Re: Solution to the rear O2 CEL (slugII)*

How would a heat sink that is wrapped around the sensor keep heat away from the sensor? And the 2nd o2 sensor doesn't sense any particular gases from the exhaust gas stream, it's just there for temperature purposes.


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## tsuter (Dec 25, 2003)

The reason the CEL pops is that the CAT doesn't always get hot enough (efficient DP and all) to catalyze all the bad stuff and the rear sensor sniffs that out.
The rear o sensor is heated by wire so that it will work. What he has done is remote the sensor enough so that it is not sniffing the bad stuff going by. Hence no CEL.
The front o sensor controls mixture with the ecu so mixture and performance is not affected.
The only effect in remoting the rear one a bit is it is not quite as sensitive now to the EG going by post CAT.


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (Power5)*

wow! this thread is taking off.








Power5... i haven't done any real data logging yet, but at idle i was at 0.47 volts (which maps to the Stoichiometric region) using the 2 arrester setup; i failed to do anything with the preivous 2 configurations.








none the less, you shouldn't be using the sensor downstream of the cat for your a/f gauge!
Dizzy.. the code appears from an insufficient difference in the front and rear sensors.










_Modified by kdub790 at 8:05 AM 4-30-2004_


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## SlvrBllt (Oct 15, 2001)

*Re: Solution to the rear O2 CEL (kdub790)*


_Quote, originally posted by *kdub790* »_
I elected to start off with the 42002 (tapered) only, which is the longer of the two, this worked out fine for 120 miles. 

So you added the second one because you were getting a CEL? Or were you just experimenting?
GREAT FIND!!!


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (slugII)*


_Quote, originally posted by *slugII* »_A heat sink would reduce the temp of the sensor which would not help.
I think all it's doing is moving the sensor further away from the exhaust stream. Thereby reuducing the concentration of pollutants being sensed by the sensor. 
So the sensor is perceiving a cleaner exhaust just because it is moved further away.
The trick is to get the right level of exhaust on that sensor because too little heat will throw a code. That's why you have to play with the fitment distance with multiple pieces to get the correct result.
If this works, it leads me to believe that the cause of this code is not so much the temp of the sensor but, actual catalytic converters that aren't doing their job scrubbing the exhauts.


what he said. http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif 
Dizzy...there is not heatsink here, just adding a gap. instead of the sensor sitting directly in the flow, it has been recessed.


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_
So you added the second one because you were getting a CEL? Or were you just experimenting?
GREAT FIND!!!

i still had those _420 blues_.








the second one went in unmolested (no drilling). some of the wrx guys drill through both.


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## jeller (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

so I should only drill out one of them or both of them? only one of yours is drilled, correct?


_Modified by jeller at 12:49 PM 4-29-2004_


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## BoostedGolf02 (Sep 21, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

Soo you tired out the 42009(drilled) and then your got a cell at 120 miles. Then you just added the 42002(the way it is) in front and Eureka ! ! ! Sweeeet. I'm sooo down to try this. Soo in total it was like 10 bucks? Let us know....how many miles now...


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (jeller)*

*the base is not drilled*, the one the sensor goes in has to be drilled for obvious reasons.


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## jeller (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

Thanks, great info, hope this works, It will make me soo happy not to have to look at that fooking light anymore


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (BoostedGolf02)*


_Quote, originally posted by *BoostedGolf02* »_Soo you tired out the 42009(drilled) and then your got a cell at 120 miles. Then you just added the 42002(the way it is) in front and Eureka ! ! ! Sweeeet. I'm sooo down to try this. Soo in total it was like 10 bucks? Let us know....how many miles now...

i believe one package of either the 42009 or 42002 was about $5.50 here in dallas. i went ahead and purchased one of each which gave me 4 total pieces. what i might reccomend is to use the 42009's (the one's with the crush gasket and are shorter in length), with one drilled and one not... this will maximize the ground clearance.










_Modified by kdub790 at 12:02 PM 4-29-2004_


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## mwwVW (Mar 31, 2003)

*Re: Solution to the rear O2 CEL (Power5)*


_Quote, originally posted by *Power5* »_do you know what the output change is? I use that for my A/F gauge at the moment, so if this kills its accuracy, I dont want to do it. Just wondering.

wouldnt it make more sense to utilize the front o2 sensor as the data the rear o2 sensor reads has already been "tampered" with by the cat? i would assume that the "data" the a/f guage would display should be unaltered as it leaves the engine...


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## JettaRed (Aug 14, 2000)

*Re: Solution to the rear O2 CEL (Power5)*


_Quote, originally posted by *Power5* »_do you know what the output change is? I use that for my A/F gauge at the moment, so if this kills its accuracy, I dont want to do it. Just wondering.

You should be using your front o2 sensor for your a/f gauge; not the rear one.


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## dex (Nov 5, 2001)

*Re: Solution to the rear O2 CEL (JettaRed)*

This deserves a place in the FAQ! http://****************.com/smile/emthup.gif


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## turbotuner20V (Mar 16, 2004)

*Re: Solution to the rear O2 CEL (dex)*

nice idea for those whose downpipes aren't functioning up to spec.... now how about those people that are running no cat? You guys think this will work also, anybody w/ no cat wanna give it a try?


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (turbotuner20V)*


_Quote, originally posted by *turbotuner20V* »_nice idea for those whose downpipes aren't functioning up to spec.... now how about those people that are running no cat? You guys think this will work also, anybody w/ no cat wanna give it a try?

*ghettlo* showed interest, may be he'll post some results.


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## mwwVW (Mar 31, 2003)

*Re: Solution to the rear O2 CEL (JettaRed)*


_Quote, originally posted by *JettaRed* »_
You should be using your front o2 sensor for your a/f gauge; not the rear one.

exactly my point above...


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## ghettlo (May 20, 2001)

*Re: Solution to the rear O2 CEL (mwwhonda)*

Well I have an ATP 3" downpipe with racepipe section coming to me as we speak. I will definitely give this a go when I install the downpipe, only problem is I dont have vag-com to clear the light when it comes on. Anyone know of a cheap tool to reset the light?


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## The Mailman (Oct 22, 2003)

*Re: Solution to the rear O2 CEL (ghettlo)*

This is awesome and I'll be trying it out on my day off next week!!!
I also heard of some JDM guys putting a heat type wrap around the rear O2 sensor - the part that actually reads the heat/gases, so it'd end up being INSIDE of your dp/test pipe. This supposedly fixed some CEL's for them. My reasoning would be that it 1) Decreases the gases sniffed by the sensore and 2) Probably kept more heat on the sensor which would fulfill that need too. I was gonna try it, but haven't got around to it and not exactly sure how I'd secure the wrap to the sensor. Any thoughts?


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## beetle18t (Feb 20, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*


_Quote, originally posted by *kdub790* »_
i believe one package of either the 42009 or 42002 was about $5.50 here in dallas. i went ahead and purchased one of each which gave me 4 total pieces. what i might reccomend is to use the 42009's (the one's with the crush gasket and are shorter in length), with one drilled and one not... this will maximize the ground clearance.









_Modified by kdub790 at 12:02 PM 4-29-2004_

Where exactly did u purchase these parts?


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## jeller (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (beetle18t)*

Look again at first post, under parts and tools required


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## JettaRed (Aug 14, 2000)

*Re: Solution to the rear O2 CEL (slugII)*

The o2 sensor doesn't sniff pollutants; it senses oxygen. Hence, oxygen _sensor_.


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## evilpat (Feb 26, 2002)

*Re: Solution to the rear O2 CEL (JettaRed)*

here is a little on how the sensors work for those that are confused . . .
_An Oxygen sensor is a chemical generator. It is constantly making
a comparison between the Oxygen inside the exhaust manifold and air
outside the engine. If this comparison shows little or no
Oxygen in the exhaust manifold, a voltage is generated. The
output of the sensor is usually between 0 and 1.1 volts. All
spark combustion engines need the proper air fuel ratio to
operate correctly. For gasoline this is 14.7 parts of air to one
part of fuel. When the engine has more fuel than needed, all
available Oxygen is consumed in the cylinder and gasses leaving
through the exhaust contain almost no Oxygen. This sends out a
voltage greater than 0.45 volts. If the engine is running lean,
all fuel is burned, and the extra Oxygen leaves the cylinder and
flows into the exhaust. In this case, the sensor voltage goes
lower than 0.45 volts. Usually the output range seen seen is
0.2 to 0.7 volts.
The sensor does not begin to generate it's full output until it
reaches about 600 degrees F. Prior to this time the sensor is
not conductive. It is as if the circuit between the sensor and
computer is not complete. The mid point is about 0.45 volts.
This is neither rich nor lean. A fully warm O2 sensor *will not
spend any time at 0.45 volts*. In many cars, the computer sends
out a bias voltage of 0.45 through the O2 sensor wire. If the
sensor is not warm, or if the circuit is not complete, the computer
picks up a steady 0.45 volts. Since the computer knows this is
an "illegal" value, it judges the sensor to not be ready. It
remains in open loop operation, and uses all sensors except the
O2 to determine fuel delivery. Any time an engine is operated
in open loop, it runs somewhat rich and makes more exhaust
emissions. This translates into lost power, poor fuel economy
and air pollution.
The O2 sensor is constantly in a state of transition between high
and low voltage. Manfucturers call this crossing of the 0.45
volt mark O2 cross counts. The higher the number of O2 cross
counts, the better the sensor and other parts of the computer
control system are working. It is important to remember that the
O2 sensor is comparing the amount of Oxygen inside and outside
the engine. If the outside of the sensor should become blocked,
or coated with oil, sound insulation, undercoating or antifreeze,
(among other things), this comparison is not possible.
_


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## ghettlo (May 20, 2001)

*Re: Solution to the rear O2 CEL (evilpat)*

Well if people can clamp the map sensor why cant you clamp the o2 sensor with a diode? Seems to me that if you used a multimeter and tested the values the sensor was outputting you could put a diode of the wattage inline and solve this problem completely.


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## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (ghettlo)*


_Quote, originally posted by *ghettlo* »_... you could put a diode of the wattage inline and solve this problem completely.

one of the main purposes of this mod is that is non-permanent, so you do not have to hack up your O2 sensor harness. it is just another alternative... _it's all about the options._ http://****************.com/smile/emthup.gif


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## DevX (May 24, 2002)

I wonder why no company has produced a reliable rear O2 sim or why they don't offer code removal options. GM guys have been doing this for a long time.


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## JettaRed (Aug 14, 2000)

*Re: (DevX)*


_Quote, originally posted by *DevX* »_I wonder why no company has produced a reliable rear O2 sim ....


Hmmm...I wonder, too.
Maybe it's because it is considered ILLEGAL by most states to disable emission controls. While not technically disabling an emission control, an O2 sim has the same effect.


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## cburkart (Jan 10, 2000)

*Re: (JettaRed)*


_Quote, originally posted by *JettaRed* »_Maybe it's because it is considered ILLEGAL by most states to disable emission controls.

That doesn't seem to be a problem for makes other than VW. Maybe we're still a pretty small market (or at least perceived as such).


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## JettaRed (Aug 14, 2000)

*Re: (cburkart)*

Are there companies that manufacture o2 sims for other brands? I don't know. But, if there are, I'm sure there is an "off-road use only" disclaimer.


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## cburkart (Jan 10, 2000)

*Re: (JettaRed)*

Here's a pile of them. Technically, even a chip is probably for "off-road" use only; Neuspeed is the only chip maker who has a CARB exemption for their chips. CARB is of course more strict than federal emissions regulations, so that may not be the best example. It is a common modification, though.
Even though an O2 sim more directly effects the emissions controls, most mods are probably just as illegal, so if it's something you're worried about you should just leave your car stock.


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## DevX (May 24, 2002)

*Re: (JettaRed)*


_Quote, originally posted by *JettaRed* »_Are there companies that manufacture o2 sims for other brands? I don't know. But, if there are, I'm sure there is an "off-road use only" disclaimer.

Yes, quite a few.
Yes in fact they do.
All mods for these cars are exactly "legal"?


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## JettaRed (Aug 14, 2000)

*Re: (DevX)*

What about this? --> http://www.rodney.chalker.com/o2_simulator.htm


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## SnowGTI2003 (Jan 8, 2004)

*Re: (cburkart)*


_Quote, originally posted by *cburkart* »_Here's a pile of them. Technically, even a chip is probably for "off-road" use only; Neuspeed is the only chip maker who has a CARB exemption for their chips. CARB is of course more strict than federal emissions regulations, so that may not be the best example. It is a common modification, though.
Even though an O2 sim more directly effects the emissions controls, most mods are probably just as illegal, so if it's something you're worried about you should just leave your car stock.

The Split Second Boost control system also carries a CARB EO#.


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## JettaRed (Aug 14, 2000)

*Re: Solution to the rear O2 CEL (kdub790)*

Well, I installed this fix tonight. I'll also post if I get DTCs again.


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## Holksvagon (Jun 13, 2003)

Now would a faulty CAT cause that CEL if I do not have a Downpipe... "Catalyst below Effiecncy Threshold"


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## kdub790 (May 27, 2003)

*Re: (Holksvagon)*


_Quote, originally posted by *Holksvagon* »_Now would a faulty CAT cause that CEL if I do not have a Downpipe... "Catalyst below Effiecncy Threshold"

if you still have the stock downpipe, then *yes*. the cat can become damaged and rendered ineffective, or overtime it will deteriorate and eventually not perform up to spec.


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## Holksvagon (Jun 13, 2003)

thx.... when I get the CAT changed out should the stealer replace the O2 sensors as well


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## black2001aww (Sep 30, 2001)

*Re: (Holksvagon)*

HA, I work at advance auto and today, at work, purchased these two items (42002 and 42009). I will be drilling them out soon and installing tommorrow night. I have a 3" high flow cat, but it is used and ever 300 miles I get the dreadful CEL. So I'll let you know how it goes. http://****************.com/smile/emthup.gif innovative help parts. They help more than they know.


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## AkVdub (Jan 4, 2002)

*Re: (black2001aww)*

going to buy this right now








now if we could fix the MAF's this easy


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## kdub790 (May 27, 2003)

*Re: (black2001aww)*


_Quote, originally posted by *black2001aww* »_I will be drilling *them* out soon

please post results. i'm sure my solution won't be right for everybody. 
i would start out by only drilling the one the sensor goes in, once you drill you can't go back.


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## black2001aww (Sep 30, 2001)

*Re: (kdub790)*

Two per package and only $3 per package, I ain't scared.







Group buy on Help/Motormite products?


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## jeller (Apr 18, 2002)

*Re: (black2001aww)*

Put mine in today, had code cleared and so far so good http://****************.com/smile/emthup.gif gotta give it some time though. Took me a little while to dremmel it out after drilling it. The biggest bit I had was a 1/2" so left a good amount to make it fit. Thanks hope this continues working http://****************.com/smile/emthup.gif


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## mwwVW (Mar 31, 2003)

*Re: (kdub790)*

any mileage update KDUB?


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## Ken1.8T (Feb 16, 2001)

*no go...*

Well, I have the APR DP and the rear sensor is mounted parallel with the ground and the wire is already close to the heat shield, so putting on those non foulers will cause the sensor to hit the shield. Any suggestions?


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## JettaRed (Aug 14, 2000)

*Re: no go... (Ken1.8T)*


_Quote, originally posted by *Ken1.8T* »_Well, I have the APR DP and the rear sensor is mounted parallel with the ground and the wire is already close to the heat shield, so putting on those non foulers will cause the sensor to hit the shield. Any suggestions?

The same is with the GHL DP. I have a 2.5" and I can fit the longer one. However, I don't think I could stack 'em.


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## GT143 (May 3, 2004)

*Re: no go... (JettaRed)*

Kdub790
Has Fuel consumption suffered? I tried a similar mod earlier and gas mileage worsened like 30%. Did this happen to you?


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## black2001aww (Sep 30, 2001)

*Re: no go... (GT143)*

I did mine tonight. We drilled out the tapered one and then used a die grinder with a carbide tip. Burned right thru the first attemp! My O2 is at a 45' angle towards the ground so now it's only like 3-4 inched from the ground. Not too impressed about that, but we'll see. Cleared my codes and we'll see what happens!


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## bump909 (Jun 30, 2002)

*Re: no go... (black2001aww)*

awesome.. keep us updated man


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## kdub790 (May 27, 2003)

*Re: no go... (bump909)*

_*Mileage update:* _ maybe 50-75 additional miles (thursday was the original post)
_*Fuel consumption:*_ only one tank so far and it was +1 mpg (not enough tanks to tell yet), but certainly it has not worsened
*Stacking problem: * check the link in the first post for the scooby boards, some of the wrx guys have used elbow's, so maybe they have posted a source for a 90 degree part (hope this helps)


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## jeller (Apr 18, 2002)

*Re: no go... (JettaRed)*


_Quote, originally posted by *JettaRed* »_
The same is with the GHL DP. I have a 2.5" and I can fit the longer one. However, I don't think I could stack 'em.

I have a 3" ghl DP and I stacked them, its close to the heat shield but not touching it, it does actually sit kind of low for my liking, maybe an elbow would be better/safer. But so far so good, about 125miles since adding them, stop and go with a little highway driving.


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## kdub790 (May 27, 2003)

*Re: no go... (jeller)*

here's somethings to consider...
1) do you have a cat?
2) if needed, what direction should the elbow face (opposing exhaust flow or not)?
3) whether or not to drill (enlarge) one/both arresters?
basically, you need to determine the correct amount of exhaust gases that should reach the sensor based on what configuration is to be used. _remember, once you drill you can't go back._


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## screwball (Dec 11, 2001)

*Re: (DevX)*

i'm gonna be trying this soon. i'm anxiously awaiting to hear if the CEL's reappear.


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## black2001aww (Sep 30, 2001)

*Re: (screwball)*

125miles, no cel yet. We drilled one of the tapered ones to give the threads mor strength. The flat ones you have to bore out almost to the edge/threads, and we broke one that way. So we ended up stacking 2 tapered ones. Gotta keep drilling til you can seat the O2 ALL the way into the fouler. If this double stack of tapers works, I'm going to go down to one because of ground clearance. http://****************.com/smile/emthup.gif


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## kdub790 (May 27, 2003)

*Re: (black2001aww)*


_Quote, originally posted by *black2001aww* »_If this double stack of tapers works, I'm going to go down to one because of ground clearance. http://****************.com/smile/emthup.gif 

fyi...
that's the exact setup i ran first, and it lasted for 120 miles or so (which was a little better than the 85 mile frequency before the mod).
i don;t think this has been mentioned this before, but i'm running a ceramic coated ghl 3" dp if anybody cares.


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## black2001aww (Sep 30, 2001)

*Re: (kdub790)*

240miles, no cel and counting on two tapers... http://****************.com/smile/emthup.gif


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## kdub790 (May 27, 2003)

*Re: (black2001aww)*

hello... my name is kdub..... and i have been *CEL free for 1000 miles*.


----------



## little p (Apr 29, 2000)

*Re: Solution to the rear O2 CEL (kdub790)*

This is good stuff...My CEL comes on daily. Always the same inefficency code...


----------



## jeller (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (little p)*

about 250 miles and no cell yet, good to hear Kdub on the 1K http://****************.com/smile/emthup.gif


----------



## black2001aww (Sep 30, 2001)

*Re: Solution to the rear O2 CEL (jeller)*

Almost 300miles, no CEL... and counting


----------



## JettaRed (Aug 14, 2000)

*Re: Solution to the rear O2 CEL (black2001aww)*

Well, it didn't work for me. With a little more than 300 miles, I checked my codes and found a DTC waiting to get promoted to a CEL. So all you folks thinking you're safe, throw a vag-com on and see if you have any codes.
Next step is to try stacking two of the shorter ones.


----------



## AkVdub (Jan 4, 2002)

*Re: Solution to the rear O2 CEL (JettaRed)*

yep, we have to check the dtc's ... not just the cel... i have seen the dtc without the cell for like 1000 miles once









_Quote, originally posted by *JettaRed* »_Well, it didn't work for me. With a little more than 300 miles, I checked my codes and found a DTC waiting to get promoted to a CEL. So all you folks thinking you're safe, throw a vag-com on and see if you have any codes.
Next step is to try stacking two of the shorter ones.


----------



## mwwVW (Mar 31, 2003)

*Re: Solution to the rear O2 CEL (AkVdub)*

some of the people on this board get the cel on a daily basis. if they could get away with a dtc stored in memory and a cel poping up every 1000 miles or so they would be thrilled!


----------



## black2001aww (Sep 30, 2001)

*Re: Solution to the rear O2 CEL (mwwhonda)*


_Quote, originally posted by *mwwhonda* »_some of the people on this board get the cel on a daily basis. if they could get away with a dtc stored in memory and a cel poping up every 1000 miles or so they would be thrilled!

Yes. I've had a cel for over 60,000. Now none. So I'm







.


----------



## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (JettaRed)*


_Quote, originally posted by *JettaRed* »_Well, it didn't work for me. With a little more than 300 miles, I checked my codes and found a DTC waiting to get promoted to a CEL. So all you folks thinking you're safe, throw a vag-com on and see if you have any codes.
Next step is to try stacking two of the shorter ones.

i ran a single tappered arrester first (for ground clearance) and that worked for alittle while.
what is your exact config. (cat/no cat, 1/2 arresters, etc.)?


----------



## black2001aww (Sep 30, 2001)

*Re: Solution to the rear O2 CEL (kdub790)*

3" turbo back with APR stg3 and 3" high flow cat.


----------



## screwball (Dec 11, 2001)

*Re: Solution to the rear O2 CEL (black2001aww)*

any more successes??


----------



## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (screwball)*

up to 1250 and still going strong... certainly somebody else has had similar results.


----------



## mwwVW (Mar 31, 2003)

*Re: Solution to the rear O2 CEL (kdub790)*


_Quote, originally posted by *kdub790* »_up to 1250 and still going strong... certainly somebody else has had similar results.









what down pipe are you running?


----------



## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (mwwhonda)*

3" ghl dp w/ hi-flo cat. ceramic coated to boot.


----------



## ACEdubs (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

updates!!?


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: Solution to the rear O2 CEL (kdub790)*

bump to put in history so i can read when i get home


----------



## ACEdubs (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

updates!!!!


----------



## SlvrBllt (Oct 15, 2001)

*Re: Solution to the rear O2 CEL (JettaRed)*


_Quote, originally posted by *JettaRed* »_Well, it didn't work for me. With a little more than 300 miles, I checked my codes and found a DTC waiting to get promoted to a CEL. So all you folks thinking you're safe, throw a vag-com on and see if you have any codes.
Next step is to try stacking two of the shorter ones.

Did the DTC you got say it was intermittent? If so, you may never get a CEL from it.


----------



## black2001aww (Sep 30, 2001)

*Re: Solution to the rear O2 CEL (SlvrBllt)*

No DTCs no CELs and almost 2000miles. Two tapers here. http://****************.com/smile/emthup.gif 


_Modified by black2001aww at 3:40 AM 5-26-2004_


----------



## screwball (Dec 11, 2001)

*Re: Solution to the rear O2 CEL (black2001aww)*

this weekend mine finally goes in.


----------



## cyukawa (Nov 23, 2000)

*Re: Solution to the rear O2 CEL (kdub790)*

put the 2 short ones in, last week... Drilled them both out 9/16" have driven over a week in traffic, low miles just crap traffic. and no cel's or catalyst dtc... I used to get cel's every day that I cleared them.


----------



## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (black2001aww)*

1 tapered (drilled) and 1 shorty and 2k will be my next milestone!








hey black2001aww, you're wheels are the shiznik! http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif 



_Modified by kdub790 at 8:06 AM 5-26-2004_


----------



## ACEdubs (Apr 18, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

I'm trying this next with a 3" DP and Race Pipe. We'll see. http://****************.com/smile/emthup.gif


----------



## Frosty_spl (Aug 4, 2003)

*Re: Solution to the rear O2 CEL (ACEdubs)*


_Quote, originally posted by *ACEdubs* »_I'm trying this next with a 3" DP and Race Pipe. We'll see. http://****************.com/smile/emthup.gif 

GOOD LUCK! thats what I have too.


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: Solution to the rear O2 CEL (Frosty_spl)*

Ill be doing this next week when I install my 3" w/ test pipe


----------



## Knightryder (Apr 5, 2004)

have you guys tried ponyexpress "Mil Eliminator?" I am running 3" Dp(w/out Cat) and i haven't had a code for 3 weeks...i am going to purchase the "help" set just in case pony fails! Good find !!! 
Nice clean write up too!!! http://****************.com/smile/emthup.gif 








= beer?


_Modified by Knightryder at 5:54 PM 5-26-2004_


----------



## ACEdubs (Apr 18, 2002)

*Re: (Knightryder)*


_Quote, originally posted by *Knightryder* »_have you guys tried ponyexpress "Mil Eliminator?" I am running 3" Dp(w/out Cat) and i haven't had a code for 3 weeks...i am going to purchase the "help" set just in case pony fails! Good find !!! 
Nice clean write up too!!! http://****************.com/smile/emthup.gif 








= beer?

_Modified by Knightryder at 5:54 PM 5-26-2004_

IM'd ya


----------



## RVW18T (May 6, 2004)

Has anyone experience a loss of power do to this cel


----------



## screwball (Dec 11, 2001)

*Re: (RVW18T)*

i haven't but i need it to be gone for state inspection


----------



## Knightryder (Apr 5, 2004)

*Re: (ACEdubs)*

received and responded!


----------



## jeller (Apr 18, 2002)

*Re: (Knightryder)*

Update: put in one long one and one short one, only one is drilled, I have a GHL 3" turboback, and NO cel, been over 2000 miles, stop and go driving, and a hard driving road trip to a show. I am happy not looking at the CEL anymore, http://****************.com/smile/emthup.gif to the creator and his great writeup.


----------



## JettaRed (Aug 14, 2000)

*Re: (jeller)*


_Quote, originally posted by *jeller* »_
Update: put in one long one and one short one, only one is drilled, I have a GHL 3" turboback, and NO cel, been over 2000 miles, stop and go driving, and a hard driving road trip to a show. I am happy not looking at the CEL anymore, http://****************.com/smile/emthup.gif to the creator and his great writeup. 

Which one is drilled and in what order did you stack them?


----------



## kdub790 (May 27, 2003)

*Re: (JettaRed)*


_Quote, originally posted by *JettaRed* »_
Which one is drilled and in what order did you stack them?

you *must* drill the one that the sensor is immediately attached to, otherwise it won't fit.


----------



## jeller (Apr 18, 2002)

*Re: (kdub790)*


_Quote, originally posted by *kdub790* »_
you *must* drill the one that the sensor is immediately attached to, otherwise it won't fit.

you will need a drill bit bigger than a 1/2" that is the largest I had, and then I had to dremel out the rest, took a while, if you have a bigger/the right bit it will save you alot of time.


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: (jeller)*

Bah, just drill it out and use a dremel with a carbide cutting tool. Should only take a few seconds with one of them http://****************.com/smile/emthup.gif


----------



## [email protected] (Mar 5, 2004)

*Re: (jeller)*

why don't we just demand catalytic conveters that work?
maybe it's just me, but it doesn't seem too cool to pay all this $$ for downpipe/cats that do not work properly. not to mention the additional pollution that is caused. and for what? a few more hp? not too sure where everybody lives, but in the d.c. burbs the air is just plain nasty in the summer. 
i understand that a constantly lit cel is annoying, but OBD2 is there for a very good reason. if your cel is on either your engine or pollution controls are not functioning properly. all this seems to do is to lie to the computer so the light do not come on, it does not address the real problem of an inefficient catalytic converter.
i have lots of respect for the creativity that went into this, but i say the original poster should use the talents that they obviously have to find a real solution to the problem. maybe the cat needs to be moved closer to the turbo(like the passat/a4) to recieve the correct amount of heat to work correctly. maybe engine coolant could also be used somehow???????????? these are also things that the manufactures of the larger dp/cats need to address.
one of the best reasons to buy a new vw is the fact that they are very enviromentally friendly cars, seems a little silly to me to negate this feature and go through all the cel hassles that come with it.
good luck and keep the creativity flowing
edit for spelling


_Modified by [email protected] at 3:06 PM 5-27-2004_


----------



## GTIturbo6400 (Feb 20, 2002)

*Re: ([email protected])*


_Quote, originally posted by *[email protected]* »_one of the best reasons to buy a new vw is the fact that they are very enviromentally friendly cars, seems a little silly to me to negate this feature and go through all the cel hassles that come with it.

Somehow I think that was the last reason a majority of the people in this forum bought vws....


----------



## jeller (Apr 18, 2002)

*Re: (GTIturbo6400)*

screw the grandkids, I need that couple of HP, J/K


----------



## ACEdubs (Apr 18, 2002)

*Re: (jeller)*

Hello, I live in Florida. No need for a cat.


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## kdub790 (May 27, 2003)

*Re: ([email protected])*


_Quote, originally posted by *[email protected]* »_why don't we just demand catalytic conveters that work?


the 420 CEL is not bottom line proof that the aftermarket cats are not working. the CEL is a sign that the stock cats are not working or that the ECU has detected a difference from what is expected with a stock exhaust configuration.
the true test is whether or not you can successfully pass a sniffer test, which is now required to get your state inspection in dallas, tx. this test is currently in effect in several other cities across the u.s. and several more are being added each year.
the sensor upstream of the cat (which i left untampered) is the one that the ECU uses to adjust variables (fual, air, etc.). the sensor downstream of the cat acts as a tattle-tail only. 
this mod is intended for people who may have a false CEL. with a CEL, you cannot pass inspection.








i'm not sure where you are going with the engine coolant idea, but i remember pontiac fieros having problems dripping coolant on the catalytic convertors and subsuquqntly catching on fire.


----------



## [email protected] (Mar 5, 2004)

*Re: (kdub790)*


_Quote, originally posted by *kdub790* »_
the 420 CEL is not bottom line proof that the aftermarket cats are not working. the CEL is a sign that the stock cats are not working or that the ECU has detected a difference from what is expected with a stock exhaust configuration 


if there is a difference from what is expected from stock, then they are not working. the 02 sensor has no way of reporting to the ecu what exhaust it is screwed into. it is looking for a specific resistance signal to tell the ecu if certain chemical reaction is happening(i can't remember the specific reaction it is looking for but i'm sure i could research it and find out) in other words, chemicals exiting the catalytic converter are monitored by the way they react with the probe of the o2 sensor this reaction then takes the form of a resistance signal back to the ecu. the ecu then translates this resistance signal into a pass/fail code. unless you access the basic settings function and look at block 46(i think) you will not see a pass code.
in speaking with some of the best factory trained vw techs i know, the main problem with the 3" dp/cat is that it flows so much air the cat never heats up properly, therefore it is not doing its job. this is good for hp but not the air we ALL have to breathe. most 2.5" dp/cats do seem to work properly, leading the to theory above.

_Quote, originally posted by *kdub790* »_
the true test is whether or not you can successfully pass a sniffer test, 


you are 100% correct, and i would be interestred in seeing the results(compared with stock) of an emmissions test.
we have emissions testing here also, unfortunately, we waited until it was too late, the air is very bad here. i believe we have the second worst air quality in the nation right now.

_Quote, originally posted by *kdub790* »_

the sensor upstream of the cat (which i left untampered) is the one that the ECU uses to adjust variables (fual, air, etc.). the sensor downstream of the cat acts as a tattle-tail only. 
this mod is intended for people who may have a false CEL. with a CEL, you cannot pass inspection.









i disagree with your assertion that the rear o2 sensor is a"tattle tail only" as i mentioned above the rear o2 sensor is actually measuring the efficiency of the cat. 
i also am aware that there are sometimes false CELs. the misfire codes that occured with aww awp motors are good examples.(as side note: it turned out that misfire detection was so sensitive with some of the earilest software versions, oil viscosity could cause misfire codes to occur during startup!) however, i do not believe that the majority of people getting the codes due to 3" dp/cat are getting a false CEL, there is clearly something malfuntioning in the system. your solution to the cel being on(as i said before, i commend your creativity in coming up with it) is pretty clear evidence of the fact that the catalyst system is not properly functioning. you are moving the o2 sensor just far enough out of the stream of exhaust gasses to fool the ecu into thinking the system is working, when in fact it is not.
_Quote, originally posted by *kdub790* »_

i'm not sure where you are going with the engine coolant idea, but i remember pontiac fieros having problems dripping coolant on the catalytic convertors and subsuquqntly catching on fire.










i was just thinking out-loud( or on-line







) the problem with cat eficiency seems to be related to cat temperature, or more specificly lack of temperature. i was thinking about somehow using hot engine coolant to keep the cat warm enough to maintian proper operation while providing the flow characteristics enthusiasts are looking for. good point about the fire hazzard, it makes me think that engine coolant would not be a very good way to raise cat temperature to the level that it needs to be to work. 

BTW: for those of you who do not know OG Racing, we do not sell any performance enhancing accessories of any kind for VWs. so i am not trying to sell anything or influence people to buy brand x over brand z. i am just trying to share my point of view on this issue, i hope that i have been able to add some useful information to this conversation.


----------



## Crash6 (Sep 28, 2001)

*Re: (kdub790)*

Thanks for linking me to this thread. You did a good job coming up with this fix.
It is definately a workable solution to the CEL, just not what I was hoping for. I'll probably end up doing the mod, but I am sooooo tired of doing hack-job modifications to get these damn cars running properly. [email protected] had it right; we should be asking for a properly working catalytic converter rather then tricking O2 sensors.



















_Modified by Crash6 at 7:32 AM 5-28-2004_


----------



## O2VW1.8T (Jul 9, 2003)

*Re: ([email protected])*

I just did this mod, i have no CAT I usally get a CEL around 40 miles or when i restart it 3 times or something. I've had a CEL for 50k miles i will be happy if it goes away wooohoooo lol


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## JettaRed (Aug 14, 2000)

*Re: (2001GTi18t)*


_Quote, originally posted by *2001GTi18t* »_I just did this mod, *i have no CAT *I usally get a CEL around 40 miles or when i restart it 3 times or something. I've had a CEL for 50k miles i will be happy if it goes away wooohoooo lol


You're kidding, right?


----------



## Siggy1.8T (May 25, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*

Hey can someone please check out this 02 sensor extension and let me know what you think. *http://www.flat4engineering.com/flash/index.htm * you will have to go to turbo, then to up/down pipe.
if this wouldnt work would anyone who has successfully done this mod be interested in building me a unit and i will pay respectably. im desperate and i would rather have someone do the mod that knows how to do it. i have a 2.5" techtonics with high flow cat


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## ghettlo (May 20, 2001)

*Re: Solution to the rear O2 CEL (Siggy1.8T)*

Can anyone snap a pic of how low the sensor sits after using two of these spark plug arresters? If these sit too low I might have a friend make me one that is more of an elbow to get it away from the ground.


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## JettaRed (Aug 14, 2000)

*Re: Solution to the rear O2 CEL (ghettlo)*


_Quote, originally posted by *ghettlo* »_Can anyone snap a pic of how low the sensor sits after using two of these spark plug arresters? If these sit too low I might have a friend make me one that is more of an elbow to get it away from the ground.

It depends on your DP. Mine is a GHL 2.5" and the rear o2 sensor is horizontal to the ground. I will have to drop it down to get a long and short arrestor on, then it should fit, but tightly.
BTW, 9/16" is NOT the right size!







Those flippin' drills are expensive and I had to get a 5/8" after spending $14 on a 9/16". The diameter of the o2 sensor is 15mm and 9/16" is 14.3mm. Also, I could only drill out the longer arrestor and not all the way. You only have to drill down about 3/16" to get the o2 sensor to fit.


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: Solution to the rear O2 CEL (Siggy1.8T)*


_Quote, originally posted by *Siggy1.8T* »_Hey can someone please check out this 02 sensor extension and let me know what you think. *http://www.flat4engineering.com/flash/index.htm * you will have to go to turbo, then to up/down pipe.
if this wouldnt work would anyone who has successfully done this mod be interested in building me a unit and i will pay respectably. im desperate and i would rather have someone do the mod that knows how to do it. i have a 2.5" techtonics with high flow cat
if it works (ill find out this weekend after i install my dp) ill make you o9ne and you can drive up here and get it


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## feuerdog (Feb 11, 2002)

Don't ttake this the wrong way guys, but here's what I think:
1. It's not the cat's fault for not being hot enough to be efficient,...maybe it's the fact that some of us just are running with far larger exhausts than we need for the power we are making. If we were all making 300+ HP into our big high-flow cats, then i'd bet we wouldn't have these CEL's so often.
2. I have a chipped 1.8t with a GHL 3" TB and i've had my CEL for almost as long as i've had the exhaust. But because I know this is a huge exhaust, and I know what the CEL is for,(and check it somewhat regularly) I live with it.
3. While this is an excellent little mod(one that I have been looking for for a long time), it should be noted that this is..... 
*NOT A FIX OF THE PROBLEM*(catalyst inefficiency below thresehold),
....... it is merely the *HIDING OF A POOR EMISSIONS MEASUREMENT*. Whether that be from not making enough heat for the cat to burn correctly, or the cat being too big for the heat that we are creating.
4. It might not get you through an inspection where a tailpipe emissions sniffer is used, but it will probably get you through an OBD inspection.

Once again,....we aren't "fixing" anything,...it's just a way to trick the ECU into not throwing CEL's.
The side effect of all this is the ECU staying in the "open loop" condition:

_Quote »_Since the computer knows this is
an "illegal" value, it judges the sensor to not be ready. It
remains in open loop operation, and uses all sensors except the
O2 to determine fuel delivery. Any time an engine is operated
in open loop, it runs somewhat rich and makes more exhaust
emissions. This translates into lost power, poor fuel economy
and air pollution.

How much lost power, efficiency, etc. is unknown and probably related to too many other variables, but it certainly won't be a huge difference.

In the meantime,......i'll be installing this mod myself, soon. I'm sick of looking at that little freakin CEL all the time.










_Modified by feuerdog at 9:48 PM 5-31-2004_


----------



## forcefedjetta (Aug 14, 2003)

*Re: Solution to the rear O2 CEL (kdub790)*

anyone get this cel with eurosport dp?


----------



## The Mailman (Oct 22, 2003)

*Re: Solution to the rear O2 CEL (forcefedjetta)*

Well, I removed my crappy Caspers Electronics O2 simulator today and did this mod. I had the code cleared and so far, I'm at 213 miles of CEL free driving!!!!







I'm stoked. I've stared at that light for 15k now and it's bothered the hell outta me b/c it's a new car. BTW, I'm running a 3" dp w/ a test pipe and am using 2 of the non-tapered spark plug "non-foulers" (as they're called on the packaging).


----------



## joe18tbo112 (May 7, 2002)

yah, anyone with a eurosport dp try this? I've been clearing codes every few hunred miles until i just lived with it and have been driving with it for the last 10k miles.


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## The Mailman (Oct 22, 2003)

*Re: (joe18tbo112)*

Just give it a shot. Doesn't cost very much (>$20) and shouldn't take more than an hour (depending on what size drill bit you originally use and how much extra you have to trim out....I'd suggest starting w/ 9/16" b/c 1/2" leaves quite a bit left). I can't imagine your dp w/ test pipe being much different than any others out there. Good luck http://****************.com/smile/emthup.gif


----------



## JettaRed (Aug 14, 2000)

*Re: (The Mailman)*

Unless you are using a skinnier o2 sensor, 9/16" is *NOT* big enough. The diameter of the sensor that would fit into the arrestor is 15mm; 9/16" is 14.3mm. I had to go to a 5/8" drill.


----------



## ab8349 (Jul 18, 2002)

*Re: (JettaRed)*

<$20, actually.


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## SlvrBllt (Oct 15, 2001)

*Re: (ab8349)*

Update: this mod wont work with the APR downpipe. The o2 sensor bung is welded parralel to the ground so there isnt enough room for the sensor and one of these spacers.
Wish I had realized that before I bought a $12 drill bit


----------



## chris86vw (Feb 23, 2000)

*Re: (SlvrBllt)*

put in another bung.......


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## Siggy1.8T (May 25, 2004)

*Re: (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_Update: this mod wont work with the APR downpipe. The o2 sensor bung is welded parralel to the ground so there isnt enough room for the sensor and one of these spacers.
Wish I had realized that before I bought a $12 drill bit









hey i saw online that WRX guys are making a custom little bend where the o2 sensor is so that the extension runs parallel with the pipe and not straight into the ground. here is the link again, its the same one form the begining of this post http://forums.nasioc.com/forums/showthread.php?s=&threadid=424666&highlight=cel+fix


----------



## SlvrBllt (Oct 15, 2001)

*Re: (chris86vw)*


_Quote, originally posted by *chris86vw* »_put in another bung.......

I think it would be easier/cleaner to just fab an elbow out of some pipe and a couple of these little adapters.


----------



## The Mailman (Oct 22, 2003)

*Re: (ab8349)*


_Quote, originally posted by *ab8349* »_<$20, actually.
















I'm really getting rusty


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: (JettaRed)*


_Quote, originally posted by *JettaRed* »_Unless you are using a skinnier o2 sensor, 9/16" is *NOT* big enough. The diameter of the sensor that would fit into the arrestor is 15mm; 9/16" is 14.3mm. I had to go to a 5/8" drill.
Are these strong enough to bore out that much? That will leave almost no metal left.


----------



## JettaRed (Aug 14, 2000)

*Re: (ButteroJ)*


_Quote, originally posted by *ButteroJ* »_Are these strong enough to bore out that much? That will leave almost no metal left.

I could only partially bore out the longer arrestor, not the short ones. Once you begin to bore into the threaded area, you can easily cut off (bore through) the threaded part.


----------



## The Mailman (Oct 22, 2003)

*Re: (JettaRed)*

I bored mine all the way through (I'm using the shorter one). Without a doubt, the only thing you're leaving is the threads. I actually lost the last 1 or 2. Oh well, it's working fine and I'm at 304 miles!!!


----------



## The Mailman (Oct 22, 2003)

*Re: (The Mailman)*

Well, I was afraid if I kept posting my success, that I'd jinx myself and sure enough, at 314 my CEL came on. I'm not sure the code yet b/c I don't have a VAG, but I'm sure it's for this. My fuel light had just come on a few miles before that, but I doubt low fuel could trigger anything. 
I'm running a 3" w/ a test pipe. Anyone else running this setup w/ success?? I'm using the 2 smaller ones...maybe time to put an undrilled tapered one in??


----------



## chris86vw (Feb 23, 2000)

*Re: (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_
I think it would be easier/cleaner to just fab an elbow out of some pipe and a couple of these little adapters.

easier yes, cleaner.. how the hell can 20 fittings in a row be cleaner then siomply welding in another bung. heck the one you have there now can he used for wideband tuning...


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## kdub790 (May 27, 2003)

*Re: (chris86vw)*


_Quote, originally posted by *chris86vw* »_
heck the one you have there now can he used for wideband tuning...

not if it's downstream of a cat.


----------



## kdub790 (May 27, 2003)

*Re: (The Mailman)*


_Quote, originally posted by *The Mailman* »_
I'm running a 3" w/ a test pipe. Anyone else running this setup w/ success?? I'm using the 2 smaller ones...maybe time to put an undrilled tapered one in?? 

i was unsuccessful (120 miles) with both non-foulers drilled in my original setup. if a test pipe is what i think it is, then you would need to allow even less gases from reaching the sensors. perhaps stacking some washers inside the non-fouler immediately attached to the pipe could work.


_Modified by kdub790 at 8:20 AM 6-4-2004_


----------



## jeller (Apr 18, 2002)

*Re: (jeller)*


_Quote, originally posted by *jeller* »_
Update: put in one long one and one short one, only one is drilled, I have a GHL 3" turboback, and NO cel, been over 2000 miles, stop and go driving, and a hard driving road trip to a show. I am happy not looking at the CEL anymore, http://****************.com/smile/emthup.gif to the creator and his great writeup. 

UPDATE AGAIN: My set up is listed above, no cel and going on about 3000 miles now.










_Modified by jeller at 9:53 AM 6-4-2004_


----------



## chris86vw (Feb 23, 2000)

*Re: (kdub790)*


_Quote, originally posted by *kdub790* »_
not if it's downstream of a cat.

This is true, however I Was not sure if everyone trying this was trying it with no cat or with cats that were just total POS.. 
you want a cat that works and flows exactly the same as your special high performacne one that throws codes. got to pep boys and buy a universal cat... I looked at an APR downpipe last nite and they are not 400 cell cats... they are tiny crap cats of course they wont' work.


----------



## SlvrBllt (Oct 15, 2001)

*Re: (chris86vw)*


_Quote, originally posted by *chris86vw* »_
easier yes, cleaner.. how the hell can 20 fittings in a row be cleaner then siomply welding in another bung. heck the one you have there now can he used for wideband tuning...

20 fittings? I'm going to use a 3" piece of pipe, an elbow, and a fitting on each end.


----------



## The Mailman (Oct 22, 2003)

*Re: (jeller)*


_Quote, originally posted by *jeller* »_
UPDATE AGAIN: My set up is listed above, no cel and going on about 3000 miles now.









_Modified by jeller at 9:53 AM 6-4-2004_

Guess I'll try the longer one. I'm using 2 shorter ones now (1 drilled, 1 undrilled), but I guess I'll throw an undrilled longer one on there.


----------



## black2001aww (Sep 30, 2001)

*Re: (The Mailman)*

Over 3000miles still no codes. APR stage3 3" turbo back, ATP high flow cat. Don't worry I'm going to full APR as soon as possible. 3" is just too loud and rattle too much over the past 2 years.


----------



## chris86vw (Feb 23, 2000)

*Re: (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_
20 fittings? I'm going to use a 3" piece of pipe, an elbow, and a fitting on each end.

and again how is making some sort of adapter instaed of welding in a a low profile bung cleaner? thats all I am saying. Yes it wil work, but saying its cleaned to use adapters is a little wacky.


----------



## SlvrBllt (Oct 15, 2001)

*Re: (chris86vw)*


_Quote, originally posted by *chris86vw* »_
and again how is making some sort of adapter instaed of welding in a a low profile bung cleaner? thats all I am saying. Yes it wil work, but saying its cleaned to use adapters is a little wacky.

ok, I'm really not following you here. People are using 2 adapters for this mod. I'll be using 2 adapters, and an elbow. Even if I weld in another bung, and cap my old one, I still have to use 2 adapters. 
I think I'm going to have a test pipe made with the sensor relocated like the WRX's have.


----------



## SlvrBllt (Oct 15, 2001)

*Re: (SlvrBllt)*

Installed my Home Depot elbow/extender tonight. No leaks, and no DTCs yet. I will report back in a few days.


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_Installed my Home Depot elbow/extender tonight. No leaks, and no DTCs yet. I will report back in a few days.
pics?


----------



## SlvrBllt (Oct 15, 2001)

*Re: (ButteroJ)*


_Quote, originally posted by *ButteroJ* »_pics?

I snapped a few. If it is succesful I will post them up.


----------



## JER-Z_1.8T (Jun 29, 2003)

*New DTC?*

I went 560 miles w/ no CEL or DTC untill this morning...I got a NEW one i have never seen before...anyone know what this means?
Coding: 07500, WSC: 12343
17584: Bank 1 lambda correction downstream of catalyst: control limit attained
ps: thanks for the quick fix...i went 2 weeks w/out a CEL which is much better than everyday...


_Modified by JER-Z_1.8T at 11:55 AM 6-8-2004_


----------



## kdub790 (May 27, 2003)

*Re: New DTC? (JER-Z_1.8T)*

check *this* out and see if it helps.
did you reset the ecu so that the system could adapt to the new sensor config?
i did a quick search and other people with the same code ended up having to replace either the 02 or maf sensor (surprise, surprise).


----------



## JER-Z_1.8T (Jun 29, 2003)

*Re: New DTC? (kdub790)*

thanks for the link...
i have never got this one before...maybe it's because my rear 02 sensor is not seeing enough w/ this new setup?


----------



## kdub790 (May 27, 2003)

*Re: New DTC? (JER-Z_1.8T)*


_Quote, originally posted by *JER-Z_1.8T* »_...maybe it's because my rear 02 sensor is not seeing enough w/ this new setup?

could be, but i would expect either P0136, 139, or even 140 (malfunction, slow response, or no activity). another thing to check is leaks on the intake side (especially if you have a cai).


----------



## JER-Z_1.8T (Jun 29, 2003)

*Re: New DTC? (kdub790)*

cool...will do, thanks


----------



## screwball (Dec 11, 2001)

*Re: New DTC? (JER-Z_1.8T)*

i got my stock DP put on and i'm still throwing these bastards. i guess i'm due for new 02 sensors...


----------



## Wayne92SLC (Mar 1, 2001)

*Re: New DTC? (screwball)*

Wow--these threads get buried fast!
I just installed a long drilled and shortie non-drilled. In case anyone wanted to know, a 19/32" dill bit is perfect. I tried drilling through with a 9/16" and then hogging out some material with a Dremel, but it was taking too long and looked terrible. So, I just went back to work and chucked it up in the lathe and ran a 19/32" through. Since the tip of the secondary O2 sensor measured about 0.590"--which someone already mentioned at 15mm--I figured the 19/32" would be really close (0.5938") Yup--it was. I goofed around with the other one in the set using a 5/8" bit but I went a little too deep and took the threaded section clean off.
Not a fan of the ground clearance--especially since I just installed H&R Race springs/Bilstein Sports. We'll see, I guess...
Let the mileage count begin!
-Wayne


_Modified by Wayne92SLC at 9:26 AM 6-17-2004_


----------



## kdub790 (May 27, 2003)

*Re: New DTC? (Wayne92SLC)*


_Quote, originally posted by *Wayne92SLC* »_Not a fan of the ground clearance--especially since I just installed H&R Race springs/Bilstein Sports. We'll see, I guess...
_Modified by Wayne92SLC at 9:26 AM 6-17-2004_

i believe someone has found an elbow of sorts at their local home depot. http://****************.com/smile/emthup.gif 
btw, i'm still dubbin cel free.


----------



## Wayne92SLC (Mar 1, 2001)

*Re: New DTC? (kdub790)*

Sweet--might have to stop off at "The Po" on the way home.
50 miles--CEL free








-Wayne


----------



## black2001aww (Sep 30, 2001)

*Re: New DTC? (Wayne92SLC)*

Still CEL free here and it's been 3-4 weeks I believe. Lots o' miles. http://****************.com/smile/emthup.gif


----------



## 4ceFed4 (Apr 3, 2002)

*Re: New DTC? (black2001aww)*

Would anyone be interested in splitting this ebay auction with me? It's for three 19/32" high quality drill bits. Total cost shipped is $16.45 overall, so it would be a little over $5 per person. This is a much better deal then buying them somewhere else. Let me know ASAP. 
Auction Link:
http://cgi.ebay.com/ws/eBayISA...=WD1V


_Modified by 4ceFed4 at 4:19 PM 6-18-2004_


----------



## 4ceFed4 (Apr 3, 2002)

*Re: New DTC? (4ceFed4)*

I just ended the auction using buy it now. If anyone wants one of these bits, send me an IM or email ([email protected]) and I'll sell you one for $5 plus the cost of however you want it shipped.


----------



## Siggy1.8T (May 25, 2004)

*Re: (SlvrBllt)*

hey would somebody be willing to make me an extension with an elbow for my techtonics downpipe? i can send money through paypal or something.


----------



## jetta1.8TGLS (Feb 20, 2001)

*Re: (Siggy1.8T)*

For what it's worth.....I've had the cat-insufficiency code ever since I installed a high-flow cat (about 1.5 years)....I would clear the code with a vag-com, i would always get another CEL within 20 miles or so....I never felt it was a big deal...so I didn't really bother with it.
Well just about a week ago I ordered and installed a 3" QuicktimePerformane cutout....I cleared the code before the install...The installation involved moving my cat and rear O2 sensor further down my exhaust (further away from the front O2 sensor)....I don't know if this is the reason, but i've driven at least 500 miles since the installation and no CEL....So being how often and how long I had that code in the past, it would be a far stretch to call this just a coincidense that the CEL would be gone after I installed the cutout. 
I drive mostly with the cutout in the closed position (exhaust going through the whole system), but I have driven a considerable distance with it open also....no CEL either way. 
The car also seems to pull much harder in the upper RPM's (4500-7000). Feels this way with the cutout open and closed. I haven't gotten to play around with it too much because of rain and busy days, but it definitely feels stronger now that the CEL is gone. It always seemed like the car lost its strength up top... now when I get done giving it a good lashing, I always have this weird smile on my face







. I never thought that code was hurting my performance, but it sure feels different now without it....I don't have any hard data supporting this such as dyno or track numbers, but it does feel better.
I'm not saying this would work for everyone, but it did for me. Got the best of both worlds, more power and a fixed CEL (how often do you put those two things together?







)


----------



## Luv2dub (Mar 7, 2003)

*Re: Solution to the rear O2 CEL (forcefedjetta)*

I have had this cel on a eurosport DP for about a year.I did 2 tapers and the cel went out a few days ago.
Make sure you use a 5/8 drill bit. http://****************.com/smile/emthup.gif


----------



## Wayne92SLC (Mar 1, 2001)

*Re: Solution to the rear O2 CEL (Luv2dub)*

I was screwing around in the machine shop today with a second set of the Help 42002 non-foulers (this is the longer one with the tapered end). I was telling my buddy about this way of tricking the computer since his BMW 323iS has the same issues so I was going to whip one up for him. So, anyway, I was thinking maybe this would be an elegant solution to those who are worried about ground clearance. I know it's not for everyone, but if you have access to a machine shop, it's a quick deal.
I mounted the non-fouler in a 5C collet holder and then mounted in the vise on the vertical mill. Then, instead of using a 19/32" drill and blasting all the way through, I used an end mill and plunged 0.25" of the material from the inside. This way, the small hole in the end is retained to hopefully limit the amount of exhaust the secondary O2 sensor is "sniffing", yet getting the job done using only one non-fouler to maintain a little more ground clearance. Just an idea. Since a picture is worth a thousand words, here goes...
Here's a side by side shot of an unmolested 42002 non-fouler (on the right) along with my modded one (on the left). The only notable difference here is that I milled about a 1/16" off the top to obtain a better sealing surface on the already crushed crush washer on the O2 sensor.








Here's where the magic happens... Notice the non-fouler on the left is milled out, but has a nice, flat bottom. I'm not usually a fan of flat bottoms...








A different view after milling...








A different view of the milled hex...








I'll install it and see how it goes.
-Wayne


----------



## 4ceFed4 (Apr 3, 2002)

nice work http://****************.com/smile/emthup.gif


----------



## Luv2dub (Mar 7, 2003)

*Re: Solution to the rear O2 CEL (Wayne92SLC)*

That's exactly the way i did it,I just drilled it out enough for the 02 sensor to be screwed completely in, not al the way through.I don't have a vag so i undid the battery but that didn't remove the cel.2 days later it disappeared on it's own and has not come back.

It had been on constantly for over a year, so I am very happy.


----------



## Performa (Jun 19, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*

Excellent Post! This will solve my problem!!!


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## SlvrBllt (Oct 15, 2001)

*Re: New DTC? (kdub790)*


_Quote, originally posted by *kdub790* »_
i believe someone has found an elbow of sorts at their local home depot. http://****************.com/smile/emthup.gif 
btw, i'm still dubbin cel free.









Yep, my JB weld experiment has held up for almost two weeks now. Still no CEL. I will post pics when I get home tonight.


----------



## SlvrBllt (Oct 15, 2001)

*Re: New DTC? (SlvrBllt)*

Two of the above mentioned parts, some pipe fittings from HD, dremel tool, and a little JB Weld = no CEL. I am going to have a muffler shop fab up a test pipe with something similar to this. The WRX tuners all make one with this part already welded on. 










_Modified by SlvrBllt at 8:36 PM 6-28-2004_


----------



## SlvrBllt (Oct 15, 2001)

*Re: New DTC? (SlvrBllt)*

pic fixed


----------



## Ken1.8T (Feb 16, 2001)

*Re: New DTC? (SlvrBllt)*

SlverBllt, would you break down the steps of the assembly of this mod?


----------



## epunk (Aug 30, 2001)

bump


----------



## jeller (Apr 18, 2002)

*Re: (jeller)*


_Quote, originally posted by *jeller* »_
Update: put in one long one and one short one, only one is drilled, I have a GHL 3" turboback, and NO cel, been over 2000 miles, stop and go driving, and a hard driving road trip to a show. I am happy not looking at the CEL anymore, http://****************.com/smile/emthup.gif to the creator and his great writeup. 

Another update: Getting close to 5000 miles and still CEL free


----------



## AkVdub (Jan 4, 2002)

*Re: (jeller)*

just to add my .02
coming up on ~2k miles and cel free 
also, in vag "readiness" all values are green ,where they were not before http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


----------



## SlvrBllt (Oct 15, 2001)

*Re: New DTC? (Ken1.8T)*


_Quote, originally posted by *Ken1.8T* »_SlverBllt, would you break down the steps of the assembly of this mod?

Basically I just bought some pipe and fittings, then dremeled them out until the adapters would fit and then JB welded them all together.
I am going to remove this part and try the rectifier diode that the S4 guys have had success with. Much cleaner and no worries about heat loosening the JB weld.
Info in this thread:
http://forums.vwvortex.com/zerothread?id=1462273


_Modified by SlvrBllt at 8:11 AM 6-29-2004_


----------



## The Mailman (Oct 22, 2003)

*Re: New DTC? (SlvrBllt)*

DAMN!!! I still can't get this to be "CEL free"!!!! 
I have an RVM 3" dp w/ test pipe. At first I ran 2 shorties, 1 drilled, 1 not. I ended up getting a CEL after 350 miles. I then changed to 1 tapered (unmolested) & the same drilled shorty. I went about 550 miles before my hose popped off my DV and caused a CEL. I don't have a VAG, so I was bummed. Well, 2 days later it went away on it's own convincing me that it was for the DV and that the extenders were working. Then....today...another CEL. Checked it out and, yup, it's for the cat. 
Now, I see that someone mentioned reseting the computer after this install. So, after I clear this code, should I disconnect negative battery cable for a minute or two to make sure everything is reset??? Maybe I'll have to try 2 tapereds....


----------



## DevX (May 24, 2002)

*Re: New DTC? (The Mailman)*


_Quote, originally posted by *The Mailman* »_DAMN!!! I still can't get this to be "CEL free"!!!! 


_Quote »_
I have an RVM 3" dp w/ test pipe 

Test Pipe = No cat
Of course you will throw a code.


----------



## SlvrBllt (Oct 15, 2001)

*Re: New DTC? (The Mailman)*


_Quote, originally posted by *The Mailman* »_DAMN!!! I still can't get this to be "CEL free"!!!! 
I have an RVM 3" dp w/ test pipe. At first I ran 2 shorties, 1 drilled, 1 not. I ended up getting a CEL after 350 miles. I then changed to 1 tapered (unmolested) & the same drilled shorty. I went about 550 miles before my hose popped off my DV and caused a CEL. I don't have a VAG, so I was bummed. Well, 2 days later it went away on it's own convincing me that it was for the DV and that the extenders were working. Then....today...another CEL. Checked it out and, yup, it's for the cat. 
Now, I see that someone mentioned reseting the computer after this install. So, after I clear this code, should I disconnect negative battery cable for a minute or two to make sure everything is reset??? Maybe I'll have to try 2 tapereds....









Try they rectifier mod I posted two posts up. The thread on Audiworld is very informative and was posted by an Audi tech.


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## The Mailman (Oct 22, 2003)

*Re: New DTC? (DevX)*


_Quote, originally posted by *DevX* »_
Test Pipe = No cat
Of course you will throw a code.

Therefore being the reason I'm doing this "fix"....








Other ppl have had success w/ the test pipe...I guess I just have to experiment a lil.


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## black2001aww (Sep 30, 2001)

*Re: New DTC? (The Mailman)*

A couple/few thousand miles on my 2 tapers and finally I get 3 codes for the S2 (rear O2) included impedance too low. I think my hole must have carboned over or got a piece of something blocking it. To lazy to check right now, maybe within the next week. Back to the CEL again, crap.


----------



## bump909 (Jun 30, 2002)

*Re: New DTC? (black2001aww)*

hey, well at least it gives you plenty of time to pass your inspection.. at least it will for me in MA.


----------



## stomp.13 (Jul 27, 2003)

*Re: New DTC? (bump909)*

bump


----------



## 4ceFed4 (Apr 3, 2002)

Worked for me, 500+ miles and counting.


----------



## Siggy1.8T (May 25, 2004)

*Re: (4ceFed4)*

would someone please make me an extension. ill send money through paypal. i tried the one from flat4engineering and it doesnt fit right. im desperate.


----------



## Siggy1.8T (May 25, 2004)

*Re: (Wayne92SLC)*

if itll definitely work on my techtonics downpipe i will give u like 25. is that good? is it an elbow or straight? im me or just respond on here. but ill definitely take it if it fits


----------



## screwball (Dec 11, 2001)

*Re: (Siggy1.8T)*

2 yr old apr downpipe popped this cel from day one. i just got a replacement for a cracked flex section sent a few days back. low and behold they redesigned the downpipe and i'm getting no cels w/ over a 100 miles.


----------



## SlvrBllt (Oct 15, 2001)

*Re: (Siggy1.8T)*

Sometimes I dont know why I bother to post stuff. No one ever reads it. I made my own extension and you can read about it in this thread...
http://forums.vwvortex.com/zerothread?id=1495522

But I am interested in something cleaner/neater. Maybe we can get someone to make a batch?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_Sometimes I dont know why I bother to post stuff. No one ever reads it. I made my own extension and you can read about it in this thread...
http://forums.vwvortex.com/zerothread?id=1495522

But I am interested in something cleaner/neater. Maybe we can get someone to make a batch?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_Sometimes I dont know why I bother to post stuff. No one ever reads it. I made my own extension and you can read about it in this thread...
http://forums.vwvortex.com/zerothread?id=1495522

But I am interested in something cleaner/neater. Maybe we can get someone to make a batch?

I liked this idea for the creativity and the fact that there's no loss in ground clearance, but I think a lot of people are looking for a non-permanent mechanical solution as kdub mentioned in the first line of the first post.
-Wayne


----------



## SlvrBllt (Oct 15, 2001)

*Re: (Wayne92SLC)*


_Quote, originally posted by *Wayne92SLC* »_
I liked this idea for the creativity and the fact that there's no loss in ground clearance, but I think a lot of people are looking for a non-permanent mechanical solution as kdub mentioned in the first line of the first post.
-Wayne

How is mine permanent? The elbow and the extension piece unscrew to make removal and installation easy. Just remove the sensor, then the pipe then the elbow from the original 02 bung. The 02 sensor just screws into the adapter jb welded into the piece of pipe. 
The adapters shown in this thread will NOT work with an APR downpipe as the sensor is mounted parralell to the ground. Hence the reason for my little fabrication.


----------



## john s (Nov 14, 2000)

*A little clarification on what the O2 sensor does.*


_Quote, originally posted by *feuerdog* »_Once again,....we aren't "fixing" anything,...it's just a way to trick the ECU into not throwing CEL's.
The side effect of all this is the ECU staying in the "open loop" condition:

The oxygen sensor voltage is a measure of a difference in the partial pressure of oxygen between what is in the exhaust and what is in the ambient air. All things equal, a higher concentration of oxygen will result in a higher partial pressure. But one needs to remember its underlying basis is pressure difference. Also, signal parasitic loss is a function of sensor temperature because cell resistance changes with temperature.
Taking your last assertion first (loss of closed loop control): Closed loop control of A/F ratio is done by the pre-cat sensor reading. Bad post cat sensor readings will NOT cause the ECU to abort closed loop control. The post cat sensor not only is responsible for determining adequate cat efficiency it also allows the ECU to adapt for pre-cat sensor aging. Losing the post cat readings isn’t good, but it doesn’t cause open loop operation.
Next – [we aren't "fixing" anything]
Ideally the sensor should operate a one temperature and one exhaust pressure in order to maximize repeatability of the signal. This doesn’t happen in practice. Under light loads and speeds the temperature and pressure are low and under high speeds and load the temperature and pressure are high. This is true for any size downpipe.
So why only problems with big downpipes?
A couple of possibilities. One is that the maximum load is larger with larger downpipes leading to greater temperatures. If an O2 sensor overheats it becomes sluggish to changes in oxygen pressure. That will throw a CEL. A sensor standoff would reduce sensor temperature and fix the problem. Another possibility is that turbulence occurs in the larger diameter downpipe. Ideally the sensor should see the static pressure in the exhaust pipe. But flow creates a velocity pressure and if the sensor is in the flow stream it will see some of it. A sensor standoff would move the sensor out of the high velocity stream solving the problem.
I’m not saying either one is the case, but I am saying if so then this does “fix” the problem.
Note: A low oxygen pressure difference produces a low voltage (indicates lean condition), a high difference a high voltage (rich). Oxygen concentration in the exhaust is much less than in the atmosphere, so partial pressure of oxygen is lower. As exhaust pressure in pipe increases with engine power, partial pressure of oxygen increases (lean indication) even without a change in A/F ratio. To help alleviate this effect as well as effects of temperature and aging, ECU only considers if signal is rich or lean. Not how rich or how much lean (2 states, lean or rich).


----------



## john s (Nov 14, 2000)

*Sensor Plots*


----------



## QT_GTI (Mar 20, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

nice write up..


----------



## feuerdog (Feb 11, 2002)

*Re: A little clarification on what the O2 sensor does. (john s)*

Thanks John S,
I think I understand better now. The one thing I don't like about some of the "fixes" here in the Vortex, is that some people don't take the time to understand what is actually going on when they modify something.
Your post should help, and it at least makes sense to me.
It's just seems like it takes four or five parts of several different posts before someone finally comes up with a decent explanation to something, it's frustrating.
So basically what you're saying is that this mod will have no additional detrimental effects,.....and it's function depends on a few other variables; exhaust shape/size, heat, mod depth/size etc.?


----------



## john s (Nov 14, 2000)

*Re: A little clarification on what the O2 sensor does. (feuerdog)*


_Quote, originally posted by *feuerdog* »_It's just seems like it takes four or five parts of several different posts before someone finally comes up with a decent explanation to something, it's frustrating.

Don’t get frustrated, it’s the fun part of discovery. This forum is great for exchanging info and ideas. I’ve had a stumble on acceleration that I thought was a result of ESP. If I pull out quickly into tight traffic ESP light would flash and engine go flat for about a half second. When comparing A/F ratios from another poster I noticed engine trending lean with increasing load rate. Used Lemmiwinks accel pump adjustment, now stumble gone (after all these years!). VWVortex is great!


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## bump909 (Jun 30, 2002)

*Re: A little clarification on what the O2 sensor does. (bump909)*

http://****************.com/smile/emthup.gif


----------



## jhoggle (Jun 16, 2003)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

i am having a local muffler shop custom make a 2.5" dp for me. Should I give him these instructions or will I even be throwing any cells?


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## Wayne92SLC (Mar 1, 2001)

*Re: A little clarification on what the O2 sensor does. (jhoggle)*

What kind of cat will you be using with this custom DP? If you plan on incorporating the factory VW cat, you may be o.k. Other wise, just make sure that he welds in the secondary O2 sensor bung so it aims down at a 45 degree angle so you can use a nice machined extension. (hint, hint...)








-Wayne


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## XandrewX (Mar 29, 2004)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

Here is what I made with some parts... I did not get a CEL yet on a 3" Down pipe with no cat after about 2000 miles now... I wanna make something a little more cleaner without jb weld on that last connector.. Maybe I can start making them for people as well... Let me know what you think


----------



## jhoggle (Jun 16, 2003)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

they are going to use a high flow cat. I was told that using the stock cat really would negate any gains I made from going with a 2.5" dp. Its basically going to be a 2.5" dp from the turbo to the stock exhaust. They are charging $410 installed. Brian, the giac dealer in meriatta, ga, told me that custom dp's are not as good as a manufactured dp. Is this true? Not to undermind his expertise, seems very knowledgable, just want a second opinion. http://****************.com/smile/emthup.gif thanks


----------



## jhoggle (Jun 16, 2003)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

can this be done with a eurosport 2.5" with no problems?


----------



## ghettlo (May 20, 2001)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

Never mind that idea wouldnt work.


----------



## joseaudi (Aug 3, 2004)

Will this modification work with Audi engines. Want to get the test pipe from eurocodetuning
http://ecodetuning.com/shop/ca...p=370
Anybody have experience with this? Should work right?


----------



## JettaRed (Aug 14, 2000)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

FWIW, the latest version of Revo (at least the 4 bar program) seems to have corrected the o2 sensor problem. I have gone back to just an o2 sensor with no adapters. 
Seems like they may be tricking the code, though, because the cat readiness is passed/green immediately after clearing codes.


----------



## bump909 (Jun 30, 2002)

*Re: A little clarification on what the O2 sensor does. (little p)*

http://****************.com/smile/emthup.gif


----------



## BoostedGolf02 (Sep 21, 2002)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

I made mine. I stacked the long one(drilled) and the short one(on top). Well it didnt work. I drove it for 26 iles and BAMN a cell came up. Do i need to clear this w/ a vag-com to work or just disconnecting th battery will do?


----------



## kdub790 (May 27, 2003)

*Re: A little clarification on what the O2 sensor does. (BoostedGolf02)*

you should have the dtc reset once you get the mod installed.


----------



## BoostedGolf02 (Sep 21, 2002)

*Re: A little clarification on what the O2 sensor does. (kdub790)*

dtc..huh...Well imma vag-com that sucka this week and i'll let you guys know if it works


----------



## bump909 (Jun 30, 2002)

*Re: A little clarification on what the O2 sensor does. (BoostedGolf02)*


----------



## Wolf1.8 (Mar 10, 2002)

*Re: Woo hoo! First one installed! (Wolf1.8)*

checked with a vagcom after a full day of driving....no codes and readiness is all passed!!!!!! http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif








woohoo!!


----------



## Adam20v (Apr 28, 2002)

*Re: Woo hoo! First one installed! (Adam20v)*

Still good after ~500 miles and a hard day at the drag strip








Also checked my readiness codes last night and all are PASSED...so good stuff there.


----------



## bump909 (Jun 30, 2002)

*Re: Woo hoo! First one installed! (Adam20v)*

went to install mine.. realized that the post cat o2 sensor was put in the bung before the cat (magnaflow cat with two bungs). local shop messed that one up.. lol doh! gonna fix it tonight and see what happens. still gonna install the piece anyways. http://****************.com/smile/emthup.gif


----------



## Italian GTI 1.8T (Jun 20, 2003)

*Re: Woo hoo! First one installed! (Wayne92SLC)*

http://****************.com/smile/emthup.gif


----------



## Nessal (Nov 24, 2002)

*Re: Woo hoo! First one installed! (Adam20v)*

Would this cause the car to idle bad because the 02 sensor is measuring false values?


----------



## Adam20v (Apr 28, 2002)

*Re: Woo hoo! First one installed! (Nessal)*


_Quote, originally posted by *Nessal* »_Would this cause the car to idle bad because the 02 sensor is measuring false values?

The rear 02 does not making any fueling decisions, it's strictly for emissions.


----------



## Wayne92SLC (Mar 1, 2001)

*Re: Woo hoo! First one installed! (Adam20v)*


_Quote, originally posted by *Adam20v* »_
The rear 02 does not making any fueling decisions, it's strictly for emissions.

Yahtzee! http://****************.com/smile/emthup.gif


----------



## Lorem (Nov 19, 2003)

*Re: (Wayne92SLC)*

Interesting http://****************.com/smile/emthup.gif 
Please post updates on the CEL issue.


_Modified by Lorem at 8:07 PM 9-17-2004_


----------



## Boost112 (May 8, 2002)

*Re: (SlvrBllt)*

would this work even if you dont have a cat?


----------



## Wolf1.8 (Mar 10, 2002)

*Re: (Boost112)*

has anyone else with this installed thrown a code??? I am throwing a frequent code and tripping a CEL now. I'll post up the exact code when I have access to it (it's on my laptop at home).


----------



## MrSkills68 (Sep 25, 2003)

*Re: (Wayne92SLC)*

to the original poster... is this "mod" still hjolding up?
i put in my 3" GHL dp and after 70 miles got the code but no light (thank god)
cleared it and well see what happens but am gonna give it a shot...
just curious to see what his is doing http://****************.com/smile/emthup.gif


----------



## kafercup (Sep 17, 2000)

*Re: (MrSkills68)*

This past weekend I put 1,212 miles on the car and didn't get a single Cat inefficiency code








I have noticed though that i'm occasionally getting and intermittent code for the rear O2 (non-CEL triggering) about O2 response.


----------



## Wolf1.8 (Mar 10, 2002)

*Re: (kafercup)*

true....I am NOT getting the efficiency code. I HAVE been throwing rear O2 codes and CEL's. I replaced the rear O2 sensor and same codes pop up and trigger the CEL. I have over 2K miles on this mod and I was good for probably 1500 miles and just recently I can't stop the CEL.


----------



## Jetta_A4 (May 4, 1999)

*Re: (Boost112)*

Yes, I have no cat & this adapter worked for me. My cat. was totally burned out about 2 yrs ago. Full story here: http://forums.vwvortex.com/zer...67757 
I'm at 400 miles, no CEL, no fault codes. 



_Modified by Boostin20v at 11:35 PM 10-22-2006_


----------



## Hapa88 (May 19, 2000)

*Re: (Hapa88)*


_Quote, originally posted by *Hapa88* »_Put in Wayne's part and things have been good for over 300 miles, but I just got a CEL cruising at 60mph in 5th today. I'll check it when I get home to see what caused it.









The CEL mysteriously disappeared last night.







Still haven't got a chance to VAG, but I'll keep you guys posted.


----------



## MrSkills68 (Sep 25, 2003)

*Re: (Hapa88)*

my wonderful CEL popped on today.... i hate the look of it,,, will clear it again tonite


----------



## Adam20v (Apr 28, 2002)

*Re: (MrSkills68)*

I'm at ~2000 miles with the part installed and have yet to throw a CEL or even a DTC. http://****************.com/smile/emthup.gif 
Those having problems, post your setup.
Mine is a Techtonics 2.5" downpipe w/hollowed out cat


----------



## stomp.13 (Jul 27, 2003)

*Re: (Adam20v)*

My cat is shot! It rattles like ball bearings in a can. Im using this "spacer" and still not throwing any codes!


----------



## bump909 (Jun 30, 2002)

*Re: (stomp.13)*

my cat is doing the same thing lately. i think i'm just gonna gut it and call it a day!


----------



## Wolf1.8 (Mar 10, 2002)

*Re: (bump909)*

my setup: 3" GHL TB...w/ cat...exhaust is the same now as it was in the box. Wayne's part has been installed for ~2000+ miles.
anyway...here is the code I get most often:
*17584 - Bank1: O2S (Lambda) Correction Behind Catalyst: Control Limit Reached
P1176 - 35-00 - -*
According to the Bentley CD that means I need to check my rear O2 sensor which has been done (as per procedure on Bentley CD) and also the O2 sensor (post cat) was replaced.
In addition...when scanning this time I also got the following 2 codes:
*17526 - Oxygen (Lambda) Sensor Heating: B1 S2: Open Circuit
P1118 - 35-10 - - - Intermittent
17522 - Oxygen (Lambda) Sensor: B1 S2: Internal Resistance too High
P1114 - 35-00 - -*
Both codes refer to the post cat O2 sensor and the Bentley says to check that sensor. 
Any ideas on what should be done next??









_Modified by Wolf1.8 at 2:01 PM 9-28-2004_


_Modified by Wolf1.8 at 2:02 PM 9-28-2004_


----------



## 99txturbo (Oct 1, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*

The problem is that the rear O2 sensor is located too close to the cat and does not get correct readings because of insufficent amount of exhaust to sample. I have seen DP with free flow cat with O2 sensor mounted in the middle of cat. It needs to be in exactly the stock position, at the very end of convertor at the connection to exhaust pipe. This will prevent all those nasty codes. VW mounted their post cat O2 sensor at that position to measure enough exhaust at the right temp.to send the correct amount of data to the ECU. The rear O2 sensor is only there to measure if the cats. working according to pre-determined values. The front O2 sensor controls the mixture, ect and keeps it in a narrow range so the cat. can convert the polution gasses to less harmfull level. There is a post cat "simulator" that plugs into O2 wire harness and simulates a signal duplicating a cat. working with in its correct range. I forget where I saw them for sale. Re-locating the post O2 sensor tword the rear of cat. fixes all those CEL an MIL indicators. 99txturbo


----------



## Dubman1 (Apr 6, 2002)

*Re: Solution to the rear O2 CEL (99txturbo)*

Those without a cat that are using this, any good expeirence with it? Also, what is the difference between CELs, DTCs and Readiness codes? 
I wanna go with a no cat DP and i would rather not throw CELs, anyone know if this works too? http://www.ponyexpressperforma....html
Thanks. 



_Modified by Boostin20v at 12:17 AM 10-23-2006_


----------



## Dubman1 (Apr 6, 2002)

*Re: Solution to the rear O2 CEL (Dubman1)*

anyone?


----------



## Wolf1.8 (Mar 10, 2002)

*Re: Solution to the rear O2 CEL (Dubman1)*


_Quote, originally posted by *Dubman1* »_http://www.ponyexpressperforma....html


I'm curious about these http://****************.com/smile/emthup.gif 


_Modified by Boostin20v at 11:45 PM 10-22-2006_


----------



## turbotuner20V (Mar 16, 2004)

*Re: Solution to the rear O2 CEL (Wolf1.8)*

maybe yours moved it too far from the pipe? try the shorty spark plug arrestor


----------



## Adam20v (Apr 28, 2002)

*Re: Solution to the rear O2 CEL (turbotuner20V)*

I'm not sure, but I think most people that are having problems still have the cat material in their cat. I'm having success with a hollowed out cat


----------



## BoostedGolf02 (Sep 21, 2002)

*Re: Solution to the rear O2 CEL (Adam20v)*

WOuld i need to clear my comp w/ a vag-com or just disconect my battery after the install???
I disconected the battery and i still have check engine light after the install


----------



## Wayne92SLC (Mar 1, 2001)

*Re: Solution to the rear O2 CEL (BoostedGolf02)*

It's ideal to check them out using Vag-com first since you can be sure that you're dealing with any and all issues stored in memory. For example, if there were 2 or 3 problems which caused CEL's, and you took care of one, the CEL would still be on. Make sense?
That being said, I don't know if the "battery disconnect method" works--I've always checked/cleared my codes with Vag-com.
-Wayne


----------



## Dubman1 (Apr 6, 2002)

*Re: Solution to the rear O2 CEL (Wolf1.8)*

Well, if this is that sucessful for everyone, I think i may have to go for one. First things first, just the DP


----------



## Binary Star (Mar 27, 2001)

*Re: Solution to the rear O2 CEL (Dubman1)*

success for almost 3000 miles now.. i have 3" TB and my cat isnt hollowed out. best 30 bux i spent.








EDIT: my 2300 post


----------



## kdub790 (May 27, 2003)

*Re: Solution to the rear O2 CEL (Adam20v)*


_Quote, originally posted by *Adam20v* »_
I've got one person locally who is having problems. And another guy I know also. They are both getting 02 Sensor Limit Reached codes

those with this problem should try a *single* spark plug arrestor. i think the problem you are running into is the gap is too large with wayne's 90 piece. 
*GENERAL RULE:* if are having a problem that has not been resolved here, go to the scooby thread listed in the inital post and you will see that they have already conquered all of the same issues. http://****************.com/smile/emthup.gif 


_Modified by kdub790 at 5:48 PM 10-6-2004_


----------



## TRBO337 (Jun 20, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

another guy did this but his is different...here's pics of what he used...anyone know if this works or what parts he used???


----------



## turbotuner20V (Mar 16, 2004)

*Re: (Wayne92SLC)*

i may be needing one of these soon, i'm throwing codes for all sorts of 02 sensor problems. So its either the sensor or the new 3" exhaust tripping a code... hopefully i be gettin your part instead of VWs


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (20V1.8Tnut)*

Since the front O2 sensor controls the A/F mixture, if your cat is actually working (stock or high flow), using a standoff for the secondary O2 sensor shouldn't have any affect. (or is it effect?) The seondary O2 sensor is primarily there to act as an OBDII tattletail for to make sure the cat is working. It doesn't change mixture.
-Wayne


----------



## olaf (Jun 8, 1999)

*Re: (Wayne92SLC)*

So, people are still having good success with this right angle spacer? Will this part work with the oem cat too?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (olaf)*

Yup--it should work fine with the OEM exhaust. However, I would wonder why the OEM exhaust would be causing a cat inefficiency. Is your cat fouled or gutted? 
-Wayne


_Modified by Boostin20v at 11:51 PM 10-22-2006_


----------



## Dubman1 (Apr 6, 2002)

*Re: (harv2892)*

Who has had a lot of sucess with this. Anyone gone without a cat been sucessful?
Also, if you do throw a code, how do i go about clearing it? Is it true that an aftermarket headunit will F up your diagnostics. I am just trying to figure out how to clear the code if i get one. and hoping that i dont (im way to soft to have a CEL, im just a pu$$y i guess)
Thanks


----------



## MeenVR6 (Feb 24, 2004)

im not a 1.8t guy, I have a VR6 (24v) and was thinking about runing a test pipe or a stock gutted cat. I would like to just install a test pipe but, with the gutted stock cat do you guys think i would throw a cell? Im going with 2.25in piping if that matters.


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (MeenVR6)*


_Quote, originally posted by *MeenVR6* »_im not a 1.8t guy, I have a VR6 (24v) and was thinking about runing a test pipe or a stock gutted cat. I would like to just install a test pipe but, with the gutted stock cat do you guys think i would throw a cell? Im going with 2.25in piping if that matters. 

A couple people have had success with this part and a gutted cat, but there have been a couple that have not. It seems kinda like a hit or miss deal. But since it's completely reversible and cheaper than a new downpipe with cat, it may be worth a try








-Wayne


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (harv2892)*

I wonder if there is some common factor with the people that have this issue? I don't get this code and mine has been in for many months/miles. Maybe chip programming, exhaust diameter, or exhaust manufacturer? For reference, I'm running 3" GHL TB with REVO 4bar programming.
Unfortunately (and somewhat ironically), I don't think I'll ever get any codes regarding the secondary O2 sensor anymore. I just had my REVO programming updated with the big downpipe program. I guess I don't need the original angle block assembly that I made...


----------



## BoostedGolf02 (Sep 21, 2002)

*Re: (Wayne92SLC)*

I did this mod and i still get a cell withen 30 miles....i guess i'll try and drill the hole a lil bigger.
I even bought a new front 02 sensor and cleaned the rear one


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (BoostedGolf02)*

Whoa! 30 miles? That's not too good. What code is popping up?


----------



## VDUBNDizzy (Mar 12, 2003)

*Re: (Wayne92SLC)*

If control limit is reached, it has something to do with adaptation. This is the same code I get on my 3" GHL TB. Wondering if playing with adaptation values would stop the code from coming up. On another note, I took mine out a few weeks ago and haven't thrown a cat code since.







Too bad my speed sensor went bad so I have perma CEL from that.


----------



## CTSharV (Oct 29, 2003)

*Re: (VDUBNDizzy)*

I have 3" GHL TB w/ upsolute 93 software. I always used to get the cat efficiency code before, now after I installed the angle bracket, I only get the control limit reached CEL.


----------



## VDUBNDizzy (Mar 12, 2003)

*Re: (harv2892)*


_Quote, originally posted by *harv2892* »_I have 3" GHL TB w/ upsolute 93 software. I always used to get the cat efficiency code before, now after I installed the angle bracket, I only get the control limit reached CEL.

Same here except I'm on GIAC and now I don't get any codes. VW gremlins hard at work in my ECU.


----------



## CTSharV (Oct 29, 2003)

*Re: (VDUBNDizzy)*

still looking for a solution......


----------



## CTSharV (Oct 29, 2003)

*Re: (harv2892)*

bump for my retinas being burned out thanks to the CEL


----------



## MrSkills68 (Sep 25, 2003)

*Re: (harv2892)*








TTT


----------



## dengalang (Apr 19, 2004)

so does really work?


----------



## Luv2dub (Mar 7, 2003)

*Re: (Wayne92SLC)*

I did mine a while ago on a eurosport DP.I used the largest bit that wouldn't go through the side(1/2 or 5/8ths) and I haven't have a cel since it went away, probably 10,000 plus.So I would try to enlarge the whole to get he gases up around the sensor.
I used the spark arrestors you can get at advance auto.I think 2 long ones.I could checkk if any needs me to.


----------



## Knightryder (Apr 5, 2004)

400 miles no cat and no cel


----------



## BlueWater (Jul 24, 2002)

*Re: (Knightryder)*

Hi, is there any update on this? I too have the P0420 code and looking for a solution (without casuing a different problem.) Thanks


----------



## Delux247's1.8t (Apr 22, 2004)

*Re: A little clarification on what the O2 sensor does. (Wayne92SLC)*

wayne i posted this before i found this thread....tell me what you think please http://forums.vwvortex.com/zerothread?id=1728545


----------



## bigcountry02 (Apr 15, 2003)

*Re: Solution to the rear O2 CEL (kdub790)*

I throw CEL every 3,000 miles like clockwork. Always a threshold either below or exceed CEL. I *have not* done any mods what-so-ever to the car, since the first coilpack dropped in 2003. 















Rich


----------



## Blue.Jester.02Gti (Jul 31, 2002)

*Re: Solution to the rear O2 CEL (bigcountry02)*


_Quote, originally posted by *bigcountry02* »_I throw CEL every 3,000 miles like clockwork. Always a threshold either below or exceed CEL. I *have not* done any mods what-so-ever to the car, since the first coilpack dropped in 2003. 















Rich

your cat is probably bad, how many miles are on the car? the sprakplug arrestor might work for you, but if its still underwarranty, just get the dealership to replace the cat


----------



## bigcountry02 (Apr 15, 2003)

*Re: Solution to the rear O2 CEL (Blue.Jester.02Gti)*

30,440 miles on the poor thing. If the CAT is bad - I have to pay and then beg for reinbursement from VWOA, since I am stationed outside the US. German dealerships that do service US spec vehicles warranty from 2 years of the date of purchase.








Rich


----------



## bigcountry02 (Apr 15, 2003)

*Re: Solution to the rear O2 CEL (Blue.Jester.02Gti)*

Dealer advised CAT bad







; advise to return car in the mroning for CAT replacement under warranty.


----------



## Wayne92SLC (Mar 1, 2001)

*Re: Solution to the rear O2 CEL (bigcountry02)*

I hope you get reimbursed--I think the factory downpipe is a spendy piece from the dealership. If you are hesitant about VWOA paying you back, it may be worth looking into an aftermarket DP like a GHL or APR.
Good luck!
-Wayne


----------



## bigcountry02 (Apr 15, 2003)

*Re: Solution to the rear O2 CEL (Wayne92SLC)*

Dealer is doing under warranty.







They were removing one of the bolts from the exhaust amnifold and it did not want to leave - snapped and the oxygen sensor wire was burnt - had to be replaced. I was supposed to pickup today at 3:00 p.m.; however, it had to be pushed to Thursday. 
Rich


----------



## tracethesoul (Jan 1, 2005)

*Re: Solution to the rear O2 CEL (bigcountry02)*

dude,
i did this.
and it doesnt work..
ok, here are the codes...
p0136- o2 sensor circuit malfunction (bank1 sensor2)
p0138- o2 sensor circuit high volts (bank 1 sensor2)
p0172- syetem too rich (bank1)
my obd2 is not not deleting these, dont ask me why
how do i get rid of these once and for all...
its really starting to annoy me.
any suggestions?
thanks.
i really need to fix this befoure the end of next week which is when i get the parts for my turbo upgrade.
thanks agen in advance.


----------



## tracethesoul (Jan 1, 2005)

*Re: Solution to the rear O2 CEL (tracethesoul)*

if you want you can email me at
[email protected]
thanks agen


----------



## 75Grabbit (Mar 16, 2004)

*Re: Solution to the rear O2 CEL (Wayne92SLC)*

So I am about to put on a 3" DP with race section...what is going to be my best option for keeping it from throwing codes. I would like to put i on while im under there the first time. 
Thanks,
Matt


----------



## Knightryder (Apr 5, 2004)

<--- catless success story


----------



## tracethesoul (Jan 1, 2005)

*Re: (Knightryder)*

i used the HELP! parts...


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (tracethesoul)*

Can you describe which HELP! parts you used? I know some people just used one of the long non-foulers, but it wasn't enough. Most people using the non-fouler technique use one drilled out "long" extension and one short extension stacked up.
-Wayne


----------



## Fuze911 (Nov 29, 2002)

*Re: (Wayne92SLC)*

just bought a eurosport DP with a custom CB...got a code...pissing me off. After reading everysinge post on this thread im still clueless...i guess im just simple...Im going to use a long one (drilled out) and a short one (non-drilled)..is that correct...please fill me in..thx


----------



## Fuze911 (Nov 29, 2002)

*Re: (Dubbin_vr6)*

bump....very useful stuff...should be a sticky at least...


----------



## tracethesoul (Jan 1, 2005)

*Re: (Wayne92SLC)*

i stacked the 2, like in your post, drilled out one...


----------



## Fuze911 (Nov 29, 2002)

*Re: (tracethesoul)*


_Quote, originally posted by *tracethesoul* »_i stacked the 2, like in your post, drilled out one...
 the one that the 02 sensor goes into???


----------



## tracethesoul (Jan 1, 2005)

*Re: (Fuze911)*

yeah man... and its after the cat.


----------



## tracethesoul (Jan 1, 2005)

*Re: (Fuze911)*

yeah, stand alone....
custom chip
i heard a rumor that apr is makeing a program that erases that rear o2.
who knows.
if you can try contacting them see if it came out yet (apr)
let me know.


----------



## silverturbogti (May 7, 2004)

*Re: (tracethesoul)*


_Quote, originally posted by *tracethesoul* »_i stacked the 2, like in your post, drilled out one...

That is what i did, and its been close to 10k with no cel. I used 2 short ones. http://****************.com/smile/emthup.gif


----------



## Siggy1.8T (May 25, 2004)

*Re: (silverturbogti)*

has anyone heard if APR is coming out with a program to fix this issue like REVO already has?


----------



## vwguy3 (Jul 30, 2002)

*Re: Solution to the rear O2 CEL (kdub790)*

Why does APR have software at http://www.furellautowerks.com that gets rid of the rear O2 sensor and inmobiler for the engine swaps but doesn't offer it for a 1.8t in a MKIV? is because its in a new car that has to have emmision?
Thanks
Justind


----------



## Fuze911 (Nov 29, 2002)

*Re: (Siggy1.8T)*


_Quote, originally posted by *Siggy1.8T* »_has anyone heard if APR is coming out with a program to fix this issue like REVO already has?

im going have to call apr or ngp and see for myself...i think it should be free, but it most likely wont be....sux


----------



## Siggy1.8T (May 25, 2004)

*Re: (Fuze911)*

wait so is there definitely a program coming out? please let me know if you find out. i sent APR an email so i will also post if i get any word on it


----------



## jeller (Apr 18, 2002)

*Re: (Siggy1.8T)*

I have the HELP parts on my car, stacked, and one drilled out, on my GHL 3.0" turbo back, with a cat. and no cell for thousands of miles. got to be over 7500 by now. Not sure if there are codes or not, but I dont really care, just needed that damm light off, and it works for me. http://****************.com/smile/emthup.gif


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (jeller)*

When this thread first came out, I followed kdub's instructions and it worked great--one drilled out "long one" stacked with one "short one". Other than the fact that it was lowest part of the car, it worked fine for a couple thousand miles. Then I switched over to the angle block design.
-Wayne


----------



## Siggy1.8T (May 25, 2004)

*Re: (Wayne92SLC)*

APR is developing the program to deal with the downpipe issue.


----------



## tracethesoul (Jan 1, 2005)

*Re: (Siggy1.8T)*

ok, so its developing for the DP issue, but what about after the cat???
wane,
let me know how much your peace is. i think i want one, considering it is the loest part of the car. also, someone said about REVO doing a grate job? do they have a chip that eleminates this issue? 
does anyone know where i can get cheep o2 sensors for befoure and after the cat?
thanks guys,
and wane, e-mail me bro. [email protected]


----------



## 75Grabbit (Mar 16, 2004)

*Re: (tracethesoul)*

So does REVO have o2 eliminating software or not?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (derschnellstemann)*


_Quote, originally posted by *derschnellstemann* »_So does REVO have o2 eliminating software or not?

The latest update from REVO DOES eliminate CEL's caused by the secondary O2 sensor. I'm not sure of the revision, but everyone calls it the "Big Downpipe" or "Big Exhaust" revision.
-Wayne


----------



## neu318 (Feb 18, 2003)

*Re: (Wayne92SLC)*


_Quote, originally posted by *Wayne92SLC* »_
The latest update from REVO DOES eliminate CEL's caused by the secondary O2 sensor. I'm not sure of the revision, but everyone calls it the "Big Downpipe" or "Big Exhaust" revision.
-Wayne

I have the revo 4bar and a 3inch dp with racepipe and no codes, When I first put in the dp I had the 3bar program and I would get the CEL, the updated 4bar program removes the CEL, from my understanding the 3bar does not have this capability


----------



## Siggy1.8T (May 25, 2004)

*Re: (neu318)*

that is correct, and now apr is doing something to keep up


----------



## 75Grabbit (Mar 16, 2004)

*Re: (Siggy1.8T)*

Does anyone know if GIAC offers this? I am not changing chips just to fix a stupid code. 
Also, my friend has the REVO software, what all does he need in order to run this program?



_Modified by derschnellstemann at 9:39 PM 1-17-2005_


----------



## Siggy1.8T (May 25, 2004)

*Re: (derschnellstemann)*

he needs to have the 4 bar program and they add the big downpipe program to it. i beleive thats it im not sure though i am an APR man


----------



## 75Grabbit (Mar 16, 2004)

*Re: (Siggy1.8T)*


[URL]http://www.mileliminators.com
[/URL] 
Does anyone have any experience using these on your car? I know that it is a more permanent solution but I would rather be under my car once rather than 100 times.


----------



## Siggy1.8T (May 25, 2004)

*Re: (derschnellstemann)*

heard those dont work for **** cause i first looked to go that route. if you dont have to touch the electrical on a VW, dont!


----------



## Knightryder (Apr 5, 2004)

*Re: (derschnellstemann)*

i had it...and all it did was cause another code...that unit is for the cars specified...our cars are a PITA when it comes to electrical override...only bypassing i am 100% pleased with is diode on the map ...O2...4getta bout it.








I would use the money and purchase Wayne's unit or run the REVO software...i've yet to hear a solution to the rear o2 code thats bulletproof...i'm still going strong with no codes...just the usual: Boost limit exceeded, and some other dumb code..."your car aint fast if you aint got aleast 4 codes"


----------



## 01 Wolfsberg (Jul 4, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*

nice http://****************.com/smile/emthup.gif


----------



## Philly 1.8T (Jul 17, 2004)

*Re: Solution to the rear O2 CEL (Siggy1.8T)*

My CEL's been on for about 500 miles now...and it feels like my car is running like sh*t....does this cause loss of power or sluggishness?


----------



## 94volkswagen (May 18, 2002)

*Re: Solution to the rear O2 CEL (Dubman1)*

HI
A friend has a 2000 audi TT, and he is having problems with the CEL his code is P1128,and since he has a 3 inch downpipe and back ,we are thinking that there is too much flow through the o2 sensor .
let me know if anyone has any ideas as how we can fix this problem
thanks


----------



## LeMansGTi (Sep 3, 2002)

*Re: Solution to the rear O2 CEL (94volkswagen)*

sorry for reviving a old thread
having the same issue here and well the first post seems to say this is for the rear o2 sensor.

but the code i have, seems to be of the front 02 sensor. bank 1 referring to the front correect??
16804 - Catalyst System: Bank 1: Efficiency Below Threshold
P0420 - 35-00 - -


----------



## TURBOJETTA420 (Mar 16, 2004)

is it causing a code because there is too much flow and these extension pieces cause the 02 sensor to be shortened and stop causing CELs?...........................dont feel like reading through 13 pgs


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (TURBOJETTA420)*


_Quote, originally posted by *TURBOJETTA420* »_is it causing a code because there is too much flow and these extension pieces cause the 02 sensor to be shortened and stop causing CELs?...........................dont feel like reading through 13 pgs

That's one of the theories, yes. If you can get the "nozzle" out of the direct stream of exhaust, then the sensor doesn't pick up as much exhaust and is therefore tricked into thinking that cat is doing a great job.








-Wayne


----------



## TURBOJETTA420 (Mar 16, 2004)

i mite be going in to ghl to help them re-design the piece that goes over the rear axle, i'll ask them if it possible to weld some small extension pieces...........it would basicly be the samething right?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (TURBOJETTA420)*

Pretty much, I guess. The only kicker would be if you had GHL do something, it'll be a permanent part of the DP. If something needs to change, or if it didn't work, etc., you're stuck. If you read the first page of this long thread, the beauty of this mod (whether it's the non-fouler option or the angle block), is that it's a non-permanent solution. Just my opinion, but I surely wouldn't want to weld something onto my $900 GHL TB...
-Wayne


----------



## LeMansGTi (Sep 3, 2002)

*Re: (TURBOJETTA420)*


_Quote, originally posted by *TURBOJETTA420* »_i mite be going in to ghl to help them re-design the piece that goes over the rear axle, i'll ask them if it possible to weld some small extension pieces...........it would basicly be the samething right?

if GHL just looks at APR's exhuast and copies that design, people wont have the problem over the rear beam that we do now. still havent figured out why they went with the design they have now. oh well, live and learn through mistakes as they say.
and the rear beam issue doesnt have anything to do with the o2 sensor problem that people are having.


_Modified by LeMansGTi at 4:44 PM 3-17-2005_


----------



## TURBOJETTA420 (Mar 16, 2004)

*Re: (LeMansGTi)*


_Quote, originally posted by *LeMansGTi* »_
and the rear beam issue doesnt have anything to do with the o2 sensor problem that people are having.

_Modified by LeMansGTi at 4:44 PM 3-17-2005_

yes i know that, but it is causing rattles which can be annoying as hell


----------



## M Diddy (Sep 25, 2002)

*Re: (TURBOJETTA420)*

Back from the dead....
Any word on APR's update for this??? I've had my Brullen 2.5" TB with Hi-flo cat for over 2 years now and this code popped up last week and again today. Don't know why all of a sudden it's doing it, but it is...


_Modified by Boostin20v at 12:01 AM 10-23-2006_


----------



## Matt49265 (Jul 11, 2003)

*Re: (Wayne92SLC)*

has anyones car gone into a sort of "limp mode" because of this code? my car will go into limp mode and ill only be geting about 5 psi of boost.....This is the ONLY code i have when scanned with the vag com, im running APR 3" DP to the APR 3" hiflo cat.....


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (Matt49265)*

Wow--whenever I 've hit limp mode, VAG-COM has always turned up an overboost code. 
I'm not aware of the P0420 code causing any change in performance--it's only an OBDII tattle-tail code.
-Wayne


----------



## Matt49265 (Jul 11, 2003)

*Re: (Wayne92SLC)*

see when i go into limp mode vagcom turns up a bank 1 fuel delivery running lean or something to that extent


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (Matt49265)*

This mod wouldn't affect that code. The primary O2 sensor plays a part in the feedback loop in controlling the mixture. That's not to say that the primary O2 sensor is bad--just that it is picking up a problem regarding the mixture.
-Wayne


----------



## Matt49265 (Jul 11, 2003)

*Re: (Wayne92SLC)*

welp put in a 5 bar FPR and so far so good....we'll see.... no CEL and more importantly, no limp mode.


----------



## inflatin (Sep 4, 2003)

I will paypal $9 for someone to grind out a spacer and test that the o2 sensor fits in it and ship it to me. Please IM me thanx


----------



## Reese77 (Oct 20, 2004)

*Re: (Wayne92SLC)*

I just put on my APR 3" TB on yesterday threw a CEL after 20-25 miles. I cleared it with my DPP but it came one again. this after another ten minutes when I had just revved to 4k a couples of times and pulled away hard through 2nd, but not redlining. 
I know the fittings are all tight so I'm not sure what the problem is?? Any ideas??? This is annoying.


----------



## Reese77 (Oct 20, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*


_Quote, originally posted by *kdub790* »_
one of the main purposes of this mod is that is non-permanent, so you do not have to hack up your O2 sensor harness. it is just another alternative... _it's all about the options._ http://****************.com/smile/emthup.gif 

but this doesn't really fix anything right? It only masks the problem?
The other question I have is anyone passing their emmissions test with CEL on?? i read somewhere else the problem is jsut in the placement of the cenors on aftermarket downpipes. 
Do the cenors on the car lay any part in the emmisions tests or does the test use something completely different? Thanks


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: (Reese77)*


_Quote, originally posted by *Reese77* »_I just put on my APR 3" TB on yesterday threw a CEL after 20-25 miles. I cleared it with my DPP but it came one again. this after another ten minutes when I had just revved to 4k a couples of times and pulled away hard through 2nd, but not redlining. 
I know the fittings are all tight so I'm not sure what the problem is?? Any ideas??? This is annoying.
um, because your cat isnt doing its job.


----------



## Reese77 (Oct 20, 2004)

*Re: (Buttero J-Lo)*


_Quote, originally posted by *Buttero J-Lo* »_um, because your cat isnt doing its job.

It's a brand new APR tb.


----------



## Buttero J-Lo (Mar 5, 2003)

*Re: (Reese77)*


_Quote, originally posted by *Reese77* »_It's a brand new APR tb.
doesnt mean anything. i dont know what kind of cat they use, but it might not have a high enough cel count to do its job properly.


----------



## kdub790 (May 27, 2003)

*Re: (Buttero J-Lo)*


_Quote, originally posted by *Buttero J-Lo* »_um, because your cat isnt doing its job.

in dallas, tx you cannot take your test with the cel on. but this did pass the butt sniffer test.


----------



## GLI-Extreme (Jun 12, 2004)

*Re: Solution to the rear O2 CEL (jeller)*

sweet


----------



## turboman808 (May 2, 2005)

does this work if you run a test pipe with 3in exhaust, anyone with any feed back with this setup is appreciated.


----------



## michael whittaker (Jan 28, 2003)

*Re: (Buttero J-Lo)*

I'm putting on a 3" DP with 3" dump today, so if I throw a code, I'll buy one of your pieces wayne...if that's ok with you.


----------



## PcMoney01 (Feb 17, 2003)

*Re: (michael whittaker)*

17584 - Bank1: O2S (Lambda) Correction Behind Catalyst: Control Limit Reached
My "below threshold" code went away, but now I am getting this one. I replaced the rear o2 sensor thinking that it would work, but my guess was wrong.


----------



## mrvw2 (Nov 15, 2004)

*Re the cat cel*

with all of us having sooo many problems with APR cats isn't about time they stepped up to the plate and did something about it!!!! There was some talk about them rewriting their programs to eliminate this........how about it? It would be nice if they would respond direct, a cel is one thing, but when you can't get your car inspected it becomes a hugh issue.


----------



## silverturbogti (May 7, 2004)

*Re: (turboman808)*


_Quote, originally posted by *turboman808* »_does this work if you run a test pipe with 3in exhaust, anyone with any feed back with this setup is appreciated.

I made a spacer with the Help! parts. I have no CEL and I'm not running a cat


----------



## DubAdicted (Jan 21, 2003)

*Re: (PcMoney01)*


_Quote, originally posted by *PcMoney01* »_17584 - Bank1: O2S (Lambda) Correction Behind Catalyst: Control Limit Reached
My "below threshold" code went away, but now I am getting this one. I replaced the rear o2 sensor thinking that it would work, but my guess was wrong.

I just got the same code as well as a cat eff. code


----------



## JordanTampa4 (Jan 13, 2005)

*Re: Solution to the rear O2 CEL (SlvrBllt)*

i just bought an apr downpipe and the mil light just popped on. i am just wondering if i should get the spark plug adapter to move the 02 sensor back.


----------



## dlsolo (Sep 6, 2004)

APR has a software update for this... Contact your local APR rep.


----------



## TarHeelGTIToy (Nov 25, 2005)

*Re: Solution to the rear O2 CEL (JordanTampa4)*

Felt compelled to bump up this thread to let everyone know how well the "non-fouler" adapter fix works for the P0420 CEL problem. I just bought this '04 used with a GHL turbo-back exhaust. Dealer claimed the CEL fix would require a new $1000.00 factory cat to correct the problem. I did a search, found this thread, spent $6.00 on the parts and 30 minutes with my Dremel tool, disconnected the ground on the battery, and CEL is still absent from the dash 3 days later.
Thanks VWVORTEX and all the contributors to these helpful threads!


----------



## GT-ER (Feb 23, 2005)

*Re: (Wayne92SLC)*

I have a 3" CAT...and ZERO codes.


----------



## jetta1.8tbee (Aug 29, 2005)

*Re: Solution to the rear O2 CEL (kdub790)*

if i only put the " Help! Part no. 42002 " will that also work?
or i must use the 42009 also?


----------



## sundaydriver (Jun 4, 2004)

*Re: Solution to the rear O2 CEL (jetta1.8tbee)*

Could this code be related to the same issue?? BTW, running a 3" GHL turboback w/cat
17526 - Oxygen (Lambda) Sensor Heating: B1 S2: Open Circuit P1118 - 35-00
That's the only code. Heater element continuity tests good, per the Bentley. Comes back after about 3 cold starts. When it's gone, it runs good when cold. When it's here, car runs like crap when it's cold.
I've written about my problem in more detail in another post here and in th VAG-COM forum. Sorry for those that may have read it already.


----------



## Neufurstenhutte (Apr 3, 2005)

*Re: Solution to the rear O2 CEL (kdub790)*

http://****************.com/smile/emthup.gif Moderators, is there a way you can put this in the DIY or FAQ sections of the forum? THanks. 


_Modified by Neufurstenhutte at 7:58 PM 2-26-2006_


----------



## enginerd (Dec 15, 2001)

I have been runnign this not cat no cel. thumbup to wayne


----------



## Grey Mouser (Oct 30, 2003)

Does this only apply to REVO ECU's? Or what? I know that I had my REVO ECU upgraded and the CEL hasnt' come back (it's now ignored). But I may be swapping to an APR ECU.. and I don't want this to come back.


----------



## Wayne92SLC (Mar 1, 2001)

*Re: (Grey Mouser)*


_Quote, originally posted by *Grey Mouser* »_Does this only apply to REVO ECU's? Or what? I know that I had my REVO ECU upgraded and the CEL hasnt' come back (it's now ignored). But I may be swapping to an APR ECU.. and I don't want this to come back.


If you have REVO and get the big downpipe revision, you will not need this part. The new revision ignores input from the secondary O2 sensor. 
Poopy! They're taking food right off my dinner table!








-Wayne


----------



## Grey Mouser (Oct 30, 2003)

*Re: (Wayne92SLC)*


_Quote, originally posted by *Wayne92SLC* »_If you have REVO and get the big downpipe revision, you will not need this part. The new revision ignores input from the secondary O2 sensor. 
Poopy! They're taking food right off my dinner table!








-Wayne

Yes, I know this. The thing is I may be trading out for an APR ecu.(If I do, I dont want this CEL to come back) (FWIW, my friend had a 03 gti with very similar mods just APR instead of REVO and he very EASILY put great length on me).
Then again it could be a 5spd vs 6.... who knows.


----------



## [email protected] (Aug 30, 2005)

*Re: (Wayne92SLC)*

I did one spacer and my car is runnign smooth already. I am going to check for about 1000 miles.
I am wondering, can I do this mod for the front 02 sensor too?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: ([email protected])*


_Quote, originally posted by *[email protected]* »_I am wondering, can I do this mod for the front 02 sensor too?

Whatever you do, DO NOT PUT A SPACER ON THE FRONT O2 SENSOR. This front gives feedback to the computer with regard to the A/F ratio. If you mess with the orientation of it, you can really screw up your mixture.
-Wayne


----------



## InstantKarma (Jan 5, 2005)

*Re: Solution to the rear O2 CEL (.:TSRthis)*

i wa splanning on putting my downpipe back on today... good thing i saw this post first


----------



## CO Boy (Sep 24, 2001)

*Re: Solution to the rear O2 CEL (.:TSRthis)*

I've had it on for almost 5K and no cell. Recently passed PA inspection with it on. Although my pre-02 sensor just took a dump which probably has nothing to do with it. It was cheap to buy (cost) and it took longer to get the car on the lift than it did to replace.
edit, APR downpipe a couple of years old.


----------



## DCGULL (Jan 31, 2004)

*Re: Solution to the rear O2 CEL (CO Boy)*

I ran mine for about 50,000 miles and I lost the CEL! 
Funny, last August, my GHL 3" DP melted the CAT- I have no idea why. I drove with "dead cat syndrome" until this February- no CEL. Noise due to the melted cat rattling around, but no CEL.
Dave



_Modified by Boostin20v at 12:02 AM 10-23-2006_


----------



## [email protected] (Aug 30, 2005)

*Re: Solution to the rear O2 CEL (DCGULL)*

Wierd thing was I always get the Cel for this when I drive slow....and the throttle start acting all wierd after aobut 30 mins of driving....
but now its all gone tho...at least for now


----------



## .:TSRthis (Mar 4, 2005)

*Re: Solution to the rear O2 CEL ([email protected])*

Is there Giac X+ owners using an ebay downpipe and doing this mod?


----------



## MeCarTay (Mar 15, 2004)

*Re: Solution to the rear O2 CEL (dell6181)*

i dunno tho.. i kinda like the look of the cel in my gauge cluster


----------



## [email protected] (Aug 30, 2005)

*Re: Solution to the rear O2 CEL (Wayne92SLC)*

Ok...
500miles after putting both foulers I got a CEL








17526 - Oxygen (Lambda) Sensor Heating: B1 S2: Open Circuit
P1118 - 35-10 - - - Intermittent
17522 - Oxygen (Lambda) Sensor: B1 S2: Internal Resistance too High
P1114 - 35-00 - -
So any cure for this?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: Solution to the rear O2 CEL ([email protected])*


_Quote, originally posted by *[email protected]* »_Ok...
500miles after putting both foulers I got a CEL








17526 - Oxygen (Lambda) Sensor Heating: B1 S2: Open Circuit
P1118 - 35-10 - - - Intermittent
17522 - Oxygen (Lambda) Sensor: B1 S2: Internal Resistance too High
P1114 - 35-00 - -
So any cure for this?

You put them on the rear sensor, right?


----------



## [email protected] (Aug 30, 2005)

*Re: Solution to the rear O2 CEL (Wayne92SLC)*


_Quote, originally posted by *Wayne92SLC* »_
You put them on the rear sensor, right?









Yeah... lol


----------



## W_Jetta (Mar 5, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*

Does this going to work??
http://www.ecstuning.com/stage...=5051
its a universal o2s bung on ecstuning.com


----------



## [email protected] (Aug 30, 2005)

*Re: Solution to the rear O2 CEL (W_Jetta)*


_Quote, originally posted by *W_Jetta* »_Does this going to work??
http://www.ecstuning.com/stage...=5051
its a universal o2s bung on ecstuning.com

That is female on both ends. You need female on one and male on the other..no?


----------



## Wayne92SLC (Mar 1, 2001)

*Re: Solution to the rear O2 CEL ([email protected])*


_Quote, originally posted by *[email protected]* »_
That is female on both ends. You need female on one and male on the other..no? 

Pretty much...
This is just a bung that you weld onto a pipe to install an O2 sensor--if you were to add a A/F ratio gauge, for example. It may work as an extender, but you'd need to weld it onto the existing bung if you were to use it as a spacer. If it didn't work, it would be a pain to get it off and back to normal. (grind the welds to remove the spacer)
-Wayne


----------



## [email protected] (Aug 30, 2005)

*Re: Solution to the rear O2 CEL (Wayne92SLC)*

My code for
*17526 - Oxygen (Lambda) Sensor Heating: B1 S2: Open Circuit
P1118 - 35-10 - - - Intermittent*
Won't go away. I did check the wiring and the connections and they are all fine...







What is this mean? Sensor is bad now?


----------



## my_GTI-02 (Jan 5, 2005)

ok confused...do you drill both peices or only 1? installing exhaust in the morning so need to know soon


----------



## A1.8T (Oct 1, 2002)

*Re: (my_GTI-02)*

this thing worked for me for about 3K miles and now I have the damn CEL back on. I think I might need a new O2 censor.


----------



## A2gtirulz (Dec 23, 2003)

*Re: (A1.8T)*

CEL free for 15,000 miles! WOHOO








Thanks Wayne. http://****************.com/smile/emthup.gif


----------



## hhslax1 (Apr 3, 2005)

*Re: Solution to the rear O2 CEL (ghettlo)*


_Quote, originally posted by *ghettlo* »_Well I have an ATP 3" downpipe with racepipe section coming to me as we speak. I will definitely give this a go when I install the downpipe, only problem is I dont have vag-com to clear the light when it comes on. Anyone know of a cheap tool to reset the light?

go over to advance auto parts and borrow the obd2 code scanner.....


----------



## [email protected] (Jun 12, 2006)

*HELP...*

hi there!
i spaced out my rear lambda probe about 2000 miles ago ( http://forums.vwvortex.com/zerothread?id=2657329 ) and its been fine until now.
fortunately im not getting any CELL but i did get this code:
17584 - Bank1: O2S (Lambda) Correction Behind Catalyst: Control Limit Reached
P1176 - 35-10 - - Intermittent

now a few weeks prior to this i had my sample rate of my front lambda set back to OE settings (it was on -200 milli secs).
before i gapped my rear probe i tried slowing the sample rate down to see if that would stop the CEL and efficency below threshold fault code, but ti didnt. so thats why i turned the sample rate back to OE spec as i have now spaced the lambda out!
do you think i should put my sample rate back to -200milli sec to see if that helps? 
or what else can i do?
i think maybe the rear probe is not getting enough air/gases flowing past it? tbh i think i could have drille dit out a bit better! should i try again?

so like i said, no CEL and the car drives absolutely fine!







its just annoying knowing i have this fault code!








thanks!
james









_Modified by [email protected] at 10:36 AM 9-22-2006_

_Modified by [email protected] at 10:37 AM 9-22-2006_


_Modified by [email protected] at 10:55 AM 9-22-2006_


----------



## Dubn1Point8 (Oct 23, 2005)

*Re: HELP... ([email protected])*

I got this code like a month after i had my exhaust installed and it never effected my car....about 2-3 months ago my car started to misfire and I've been tring to figure out what is causing this...Could this be the problem?? Would this mod fix the problem??
Victor


----------



## [email protected] (Jun 12, 2006)

*Re: HELP... ([email protected])*


_Quote »_hi there!
i spaced out my rear lambda probe about 2000 miles ago ( http://forums.vwvortex.com/zerothread?id=2657329 ) and its been fine until now.
fortunately im not getting any CELL but i did get this code:
17584 - Bank1: O2S (Lambda) Correction Behind Catalyst: Control Limit Reached
P1176 - 35-10 - - Intermittent

now a few weeks prior to this i had my sample rate of my front lambda set back to OE settings (it was on -200 milli secs).
before i gapped my rear probe i tried slowing the sample rate down to see if that would stop the CEL and efficency below threshold fault code, but ti didnt. so thats why i turned the sample rate back to OE spec as i have now spaced the lambda out!
do you think i should put my sample rate back to -200milli sec to see if that helps? 
or what else can i do?
i think maybe the rear probe is not getting enough air/gases flowing past it? tbh i think i could have drille dit out a bit better! should i try again?

so like i said, no CEL and the car drives absolutely fine! its just annoying knowing i have this fault code! 
thanks!
james 

just to let you guys know... 
i redrilled the non fouler better so the lambda probe could screw as far as the thread will let it and thus letting more air get to it...
that was 600 miles ago and i have not had the _control limit reached _code logged since!










_Modified by [email protected] at 5:58 AM 10-10-2006_


----------



## [email protected] (Jun 12, 2006)

*Re: HELP... (Dubn1Point8)*


_Quote »_I got this code like a month after i had my exhaust installed and it never effected my car....about 2-3 months ago my car started to misfire and I've been tring to figure out what is causing this...Could this be the problem?? Would this mod fix the problem??
Victor

hi there.

tbh i am not sure... 
you really need to get your car vag com'd so you know wat fault codes you NOW have.
thats what i would do!


_Modified by [email protected] at 8:06 AM 10-10-2006_


----------



## Galacius29 (Jun 2, 2004)

*Re: HELP... ([email protected])*

i've been looking at this thread long enough, i think it's time to make my cell go away...hopefully it'll work on my 3" ghl tb setup...hopefully...


----------



## Boostin20v (Mar 22, 2000)

*Re: HELP... (Galacius29)*

***Note Major Thread Cleaning***
This post is for discussion of P0420 and how to get around it. This post is NOT for the sale of parts relating to this issue.


----------



## Boostin20v (Mar 22, 2000)

*Re: HELP... (Boostin20v)*

was browsing the web and found this weld on solution from Vibrant Performance:








website link


----------



## twelvesorbetter (Sep 11, 2006)

*Re: Solution to the rear O2 CEL (VDUBNDizzy)*

we tried to do this on a beetle.. but there was NOT enough room in the tunnell for two spacers... 
is one going to be ineffective?


----------



## turboborra (Jan 23, 2004)

*Re: Solution to the rear O2 CEL (twelvesorbetter)*

it will for a very short time, u need two exactly, its all about the length, distance


----------



## 18T_BT (Sep 15, 2005)

*Re: Solution to the rear O2 CEL (turboborra)*


_Quote, originally posted by *turboborra* »_it will for a very short time, u need two exactly, its all about the length, distance

isnt' it always about length and distance?


----------



## twelvesorbetter (Sep 11, 2006)

*Re: Solution to the rear O2 CEL (turboborra)*


_Quote, originally posted by *turboborra* »_it will for a very short time, u need two exactly, its all about the length, distance

has anyone done it on a beetle? we cant fit two in there with the tunnell theres no clearance.


----------



## TheBeast (Jun 20, 2006)

hit up wayne92slc, i ran into the same problems


----------



## Galacius29 (Jun 2, 2004)

Just put on my spacer on the rear o2 (from wayne) and so far *500 miles and cell free* haha..
ps.. those rear o2 sensors are a %*$&& to get out, much much easier if you have a lift 


_Modified by Galacius29 at 12:22 PM 11-15-2006_


----------



## getta18t (Dec 26, 2005)

*Re: CEL free, but ....*

I have this mod on my car for about 1 month, I'm cel free but the readiness shows *cat converter not ready*, and it won't pass inspection .
Have you guys run into this before?


----------



## VDub_Turbo (Mar 17, 2006)

*Re: CEL free, but .... (getta18t)*

I just put on a 2.5inch dp with no cat and after driving about 50miles I throw a cel. Would this mod get rid of my cel?


----------



## VDub_Turbo (Mar 17, 2006)

*Re: CEL free, but .... (VDub_Turbo)*


_Quote, originally posted by *VDub_Turbo* »_I just put on a 2.5inch dp with no cat and after driving about 50miles I throw a cel. Would this mod get rid of my cel?

Anyone?


----------



## MrcinaGTI (Oct 11, 2005)

*Re: CEL free, but .... (VDub_Turbo)*


_Quote, originally posted by *VDub_Turbo* »_
Anyone?
/ yes it will


----------



## starr18t (Nov 26, 2005)

*Re: CEL free, but .... (MrcinaGTI)*

well it seems i have the code P0420 and a fellow vortexer pointed me to this thread. My question is...If i dont have enough clearance to put the arrester in what can i do. Here is a pic...as you can see if there is another piece coming out of the DP then i'll be stuck against the firewall. Someone mentioned a 90 degree piece maybe. Thanx for any help.
Someone mentioned to contact the local APR dealer and they can correct the software. Is this true?










_Modified by starr18t at 7:13 PM 12-11-2006_


----------



## MrcinaGTI (Oct 11, 2005)

*Re: CEL free, but .... (starr18t)*

yeah, there is a guy here selling those things. They are $35 and they are 90d. It would fit nice on ure car. Now someone tell him where he can purchase one of those things.


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## starr18t (Nov 26, 2005)

yes please tell me who i can buy one from, i'll be happy to paypal ya....you would make my day i tell ya. Feel free to IM me or ill be checking this thread


----------



## el_padrino81 (May 18, 2004)

*Re: Solution to the rear O2 CEL (kdub790)*

my engine lights been on for 3 days now, scanned it and got "catalyst system efficiency too low". 
now in order to renew my plate sticker gotta go for emissions test, will this effect it?? will this mod help pass it??

i put new o2 sensors, new catylic converter, new fuel filter, all were installed within 1 year.


----------



## VeeDubbinJetta91 (Aug 19, 2002)

*Re: Solution to the rear O2 CEL (el_padrino81)*

did this mod a few weeks back after getting the cel...been cel free for over 1k miles now http://****************.com/smile/emthup.gif


----------



## slugII (Apr 5, 2002)

*Re: CEL free, but .... (MrcinaGTI)*


_Quote, originally posted by *MrcinaGTI* »_yeah, there is a guy here selling those things. They are $35 and they are 90d. It would fit nice on ure car. Now someone tell him where he can purchase one of those things.









Yeah I have a beetle and I have one of those fittings, I think the guy's name is G60 something or other and I believe he's in Minnesota.
It's a 90 degree fitting installs great.
I have a 2.5" GHL DP and a 2.75" jettex cat back with a kinetic super ko4 turbo kit.
My CEL is gone.


----------



## starr18t (Nov 26, 2005)

thanx guys he found me


----------



## Wayne92SLC (Mar 1, 2001)

*Re: CEL free, but .... (slugII)*


_Quote, originally posted by *slugII* »_
Yeah I have a beetle and I have one of those fittings, I think the guy's name is G60 something or other and I believe he's in Minnesota.
It's a 90 degree fitting installs great.
I have a 2.5" GHL DP and a 2.75" jettex cat back with a kinetic super ko4 turbo kit.
My CEL is gone.

G60 something?!?! Oh, dude...















-Wayne


----------



## President Lincoln (Jun 27, 2005)

*Re: CEL free, but .... (Wayne92SLC)*

Bump for a kick A$$ thread.


----------



## playr158 (Aug 30, 2005)

*Re: Solution to the rear O2 CEL (el_padrino81)*

hate to say this mod won't help you out too much if they sniff your tail pipe and the readings are out of accepted ranges, you have defective equipment..
the only thing this mod does is trick the ECU not your tester


----------



## starr18t (Nov 26, 2005)

*Re: Solution to the rear O2 CEL (playr158)*

I think i've tried everything and still have a problem. I bought the 90 degree piece from wayne on here to seperate the bung from the o2. I also had the test pipe file run on my car. So i still have code P0420 and the check engine light. Should i try a different brand of o2 sensor? what are my options? please help
So emmissions are a no go for me too? This just keeps getting better and better


----------



## dat (Oct 1, 2003)

*finally got the code*

well, after a few months with the new exhaust i finally got the code. i cleared it, but it came back within a month. i'm going to try the fitting from wayne so hopefully that works.


----------



## starr18t (Nov 26, 2005)

my situation was a bit different. I bout the 2.5" apr dp and the o2 sensor got crushed against the firewall and i had to replace it. So vw did that for me and tried to bang out some more room for the o2 sensor to fit. Well it worked for a while and then it got crushed again. So i went to midas where they put in another o2 sensor and make plenty of clearance room for the o2. Now my check engine light starts coming on frequently. So i bought the 90 piece. Light comes on again. I get the APR test file, and the light comes on again. So now i just ordered an OEM o2 sensor from parts4vws. If this doesnt work i'm getting advice to weld the stock cat to my dp. which i would hate doing. That is my rant folks


----------



## rono1 (Apr 23, 2002)

*Re: (starr18t)*


_Quote, originally posted by *starr18t* »_ If this doesnt work i'm getting advice to weld the stock cat to my dp. which i would hate doing. 

I'll tell you one thing forsure. i hacked up my stock DP already and at the cat there is a funnel which goes to the stock DP piping. well if you hack the funnel and Stock DP off, you actually will see that the stock CAT is 2.5in exactly!! so i think i'm going to go the same route as you.. 
Can anyone answer this, the difference between a stock cat and a hi-flow cat?
I never saw a cat before until i hacked mine off the Stock DP.. Someone mentioned cells which i believe is how many holes are in the cats design.


----------



## Mikes72sb (Oct 27, 2001)

*Re: (rono1)*

Wayne92slc spacer is great http://****************.com/smile/emthup.gif 
Over a year CEL-free (well, CEL from the O2 sensor







) Well worth the money and much easier than drilling out the "Help" spacers, and won't rust like the Help spacer http://****************.com/smile/emthup.gif


----------



## .:RPowerNY (Oct 17, 2004)

where can i get a wayne92slc spacer?


----------



## RussellsGTI (Sep 2, 2005)

*Re: Solution to the rear O2 CEL (kdub790)*

just got my CEL PO420 bc of my GHL HFcat and DP 3'' for the first time and been driving with it a little over a year. ah, time for this mod.


----------



## nogomoto (Jan 21, 2007)

*Re: (.:RPowerNY)*


_Quote, originally posted by *.:RPowerNY* »_where can i get a wayne92slc spacer?
X2. Anyone have a pic of this wayne92slc spacer? I'll get one, if I get a pic. Wanna see what I buy!


----------



## papaskot (Aug 2, 2004)

i have a spacer that i dont need anymore...IM me if you want


----------



## HighFive_GTI (May 6, 2006)

*Re: (papaskot)*

Has anyone passed emissions with the 90 degree adapter?


----------



## RussellsGTI (Sep 2, 2005)

*Re: Solution to the rear O2 CEL (RussellsGTI)*


_Quote, originally posted by *RussellsGTI* »_just got my CEL PO420 bc of my GHL HFcat and DP 3'' for the first time and been driving with it a little over a year. ah, time for this mod.


and today, 3 days later after i got my cel, its gone for now. http://****************.com/smile/emthup.gif I swear its definitely came due to driving like a grandma under 2000 rpms in 2 hour traffic with the rain/hail/snow storm L.I. had this past week. so far so good.


----------



## nogomoto (Jan 21, 2007)

*Re: (papaskot)*


_Quote, originally posted by *papaskot* »_i have a spacer that i dont need anymore...IM me if you want
 I had to leave. Sorry. Email me with info.


----------



## sle39lvr (Sep 11, 2006)

*Re: (nogomoto)*

I couldnt find thread for the longest time lol...finally back from the dead...


----------



## veeko (Oct 26, 2005)

this ended up fixing for my issue for a while. probably about 2k or so and then it completely killed my o2 sensor. luckily i found a new one for cheap.


----------



## cseaman (Jul 8, 2003)

*Re: (veeko)*

i need to hear from wayne


----------



## PAULITO (Oct 24, 2004)

*Re: (HighFive_GTI)*


_Quote, originally posted by *HighFive_GTI* »_Has anyone passed emissions with the 90 degree adapter? 

i would ike to know too


----------



## Dub-Lip (Jul 22, 2003)

*Re: (HighFive_GTI)*


_Quote, originally posted by *HighFive_GTI* »_Has anyone passed emissions with the 90 degree adapter? 

x3
im stuck my my TT downpipe and the rear o2 sits close already to the heat sheild


----------



## 1.8tPowa (Apr 1, 2007)

*Re: (Dub-Lip)*

I think I am more confused now than when I started reading this thread.... I have a GHL 2.5" tb setup and I'm running the original direct port version of the APR software. Did APR in fact update their software to fix the 0420 code? If not, could someone with a similar exhaust/chip setup reply with their fix? If there is an APR software upgrade I would rather do that then mess with installing the arrestors, but either way I need the code gone because my inspection is due here in a couple of months.


----------



## 1.8tPowa (Apr 1, 2007)

Anyone???


----------



## spoolmy1.8 (Jan 17, 2007)

*Re: (Dub-Lip)*

Yes - there are lots of people who passed inspection using wayne's 90 deg angle block. I know at least one in NY state.


----------



## spoolmy1.8 (Jan 17, 2007)

*Re: (1.8tPowa)*

I know that the APR exhaust has the bung hole horizontal and the rear O2 sensor is right next to the heat shield. Wayne's angle block keeps a good amount of space to the heat shield and you can angle the sensor so it is not close to the cat.
I don't know how long it will work for. It has been installed for 2k miles.


----------



## Woody201 (Dec 2, 2004)

*Re: (spoolmy1.8)*

i just failed emissions cause of code 420, friggin dp cell. i gave wayne a pm looking to buy a spacer. the mechanic said if i can get the light off and show him some paperwork saying that the exhaust is street leagal then he'll pass me. ive got 30 days till i gotta pay again. guy was pretty nice about it.


----------



## frag85 (May 17, 2007)

*Re: (SlvrBllt)*


_Quote, originally posted by *SlvrBllt* »_Update: this mod wont work with the APR downpipe. 

i have an APR 3" DP, and the newer ones, the bungs (haha, bung....BUNG!) are angled down.
they are angled so you can go straight out, and just clear the heat-shielding in the DP cutout under the car. will try to get a picture up.
i do believe some of this is heat related, because if i clear the below threshold code while the system is hot and continue driving at freeway speeds or very spiritedly, the code does not show up, but if i cold-start and immediately start driving i am sure to get a CEL within the next 50 miles.
edit: bah, 881 miles and i checked my ECU and the cat below threshold was there, no CEL though. i do weekly scans just because i have the means to. i had drilled through both, going to try one that i didn't drill through.


_Modified by frag85 at 5:30 PM 7-4-2007_


----------



## flashoflight77 (Nov 2, 2006)

*Re:*

i am so lost! i have a 3" DP with a test pipe and two 42002 HELP! peices... do i drill one till the O2 fits and leave the other the way it is, using both? or can i just use one the way it is and ill be fine? or just one drilled? planning on doing this in the morning so please help! TIA
Reminder...3" DP with TEST PIPE, NO CAT


----------



## r3q (Jan 21, 2007)

*Re: Solution to the rear O2 CEL (kdub790)*

i hate to bring this thread back from the dead (if it is)
but i just performed this mod to my rear O2 sensor with relative ease, and im interested to know what to do now.
i still have the CEL on the insturment panel, and i had checked with an OBD II at autozone for the "CATALYST EFFICIENCY BELOW THRESHOLD CEL P0420" code and thats all that was in there.
i heard i eaither have to complete some sort of driving cycle or use a VAG to clear the codes, i do not have a VAG or a laptop, so thats kind of out of the question.
what do i do now that i have installed a short non drilled, a long drilled, and the O2 sensor to get rid of the CEL?
thanks for any help you guys can give me, im new to this VW mod thing and id like for that code to go away asap so that i can get my inspection done!
thanks!
andrew


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## hootyburra (Feb 19, 2007)

*Re: Solution to the rear O2 CEL (r3q)*

You have to clear the CEL








Ask the zone to clear it for you or post in your regional for a vag 
or unplug the battery for a while http://****************.com/smile/emthup.gif


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## r3q (Jan 21, 2007)

so the OBD II can clear CEL codes? last time i went there they just handed me the thing and i checked the code myself.
ill drive down there right now and see what they say








ill be back in a few to report my findings.


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## r3q (Jan 21, 2007)

well i went to autozone and got the ODB II to clear the code.
we will see how long it takes for it to come back. knock on wood it stays gone with this mod!
i will keep you posted on my success.
i have 67k miles on my 03 GTi 1.8t, and i reset the mile counter after i made the modifications this morning.
wish me luck!


----------



## r3q (Jan 21, 2007)

so far 40+ miles and im good. i think this solution is working for my particular dub


----------



## r3q (Jan 21, 2007)

looks like 250 miles was when the luck ran out.
got the CEL back this afternoon.

and quite frankly, i was a bit pissed. i think im going to try and replace the 02 sensor, clear the codes and start from a clean slate. if i cant get it gone after a new sensor, them im just putting my factory cat back on. this passing inspection crap is not worth it at all.


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## bekr83 (May 17, 2006)

*Re: (r3q)*

ok guys no cel i have 400ish miles no spacer on Ej 3" car is im my sig. maybe this is hit and miss? btw as soon as i post this am sure the gremlins will show


----------



## r3q (Jan 21, 2007)

knock on wood man.
murphys law says that it will happen next time you start your engine lol


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## Brendan81 (Jul 18, 2005)

does this mod have to be done if youre stage 2? thought that software passes over this cel yet im still getting this code???


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## leon_20vt (Dec 1, 2004)

hmm, i think i should do this, maybe this weekend, i hope the auto zone here in mexico carries those things


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## r3q (Jan 21, 2007)

you do it to the rear O2 sensor on the cat (or lack therof).
the CEL on mine just came back. so im gonna go to autozone and see if i cant clear it again. it was gone for 250 miles or so


----------



## bekr83 (May 17, 2006)

*Re: (r3q)*

^yes the post cat o2


----------



## mrkrad (Nov 9, 2000)

*Re: (bekr83)*

why dont you guys just ask for the no rear o2 defeat program file.
they can disable any codes and give you readiness. its kinda how the obd-2 system is designed. as long as you get readiness bits (all on 2002+) you are good to go.
2000 models can have 2 failed and pass (ie clear codes, run basic settings test 077,071,070 then immediately go to emissions center). 2001 have to have only one not-ready so i am not sure if you can get it to 1 readiness missing before it throws a CEL. 
2002+ must have all readiness bits in (georgia) to pass. which sucks. 
but since the tuners all know how to defeat immo3/any code they want its just a matter of asking.
Unless they are CARB exempt on their chips, they can't say squat on moral standings on this topic.


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## r3q (Jan 21, 2007)

i have a GIAC chip in my 03 gti. and this is the email i got back from them.
"Hi Andrew,
Do you know what kind of high flow cat you have? Our software will throw a code if the cat has a low platinum level. We do not have an update that will turn off the software for that. When was the last update you had on your software?
Best Regards,"

i shot him an email back, ill see what he says, but i dont think they have defeat files for the O2 sensor problem.


_Modified by r3q at 8:48 AM 9-15-2007_


----------



## mrkrad (Nov 9, 2000)

*Re: (r3q)*

dude you gotta work it more low key than that. lol.


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## r3q (Jan 21, 2007)

why?
i have a performance cat, and it simply throws a code with it on. i have a (probly illigeal in virginia) mod chip for my engine, and i want a cel that i know is not a problem to go away








why are cars such a pita...


----------



## bekr83 (May 17, 2006)

*Re: (r3q)*

you think moding you car had no drawbacks?


----------



## vw collector (Jul 6, 2002)

*Re: (bekr83)*

awesome thread! I'm going to try the spacer tomorrow...


----------



## vw collector (Jul 6, 2002)

*Re: (vw collector)*

passed emissions today with no cel and readiness set. bump for saving me $$$$$$$$$


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## sickgixxer69 (Feb 24, 2007)

*Re: (vw collector)*

I tried it yesterday on my 2.0 slow and it worked. http://****************.com/smile/emthup.gif Drove over 50 miles and no check engine light and all systems go.


----------



## r3q (Jan 21, 2007)

dunno what happened.
the other day i was driving, prolly about 600 miles into the mod, 250 miles or so the light comes back on, and 550 or so the light turned back off.
*shrug*
im happy its off and i didnt have to clear it though.


----------



## Zero_Tolerance (Sep 2, 2007)

*Re: Solution to the rear O2 CEL (ghettlo)*

I tried the diode. Did it myself the first time and couldn't get it to work. In other words, couldn't figure it out. Took it to my close buddy who owns a shop here in El Paso who found a website talking about the diode mod. He took his turn and tried it, and well, didn't work. So, I now have a useless diode in my O2 sensor. It might work for someone else, but for me and all of the other cars that Bryan tried it on, nothing. Didn't fix the problem.


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## krzys84 (Sep 3, 2004)

*Re: (r3q)*


_Quote, originally posted by *r3q* »_dunno what happened.
the other day i was driving, prolly about 600 miles into the mod, 250 miles or so the light comes back on, and 550 or so the light turned back off.
*shrug*
im happy its off and i didnt have to clear it though.

I drove with this for about 15k and this morning it came back on. Dont know what happen, maybe the sensor itself went bad. Will see what happens i reset the code, if it comes back i will buy a new sensor.


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## JRjet (Jun 26, 2006)

this is kinda like the wayne angle block


----------



## Dave26 (Jan 30, 2007)

*Re: (JRjet)*

Hey guys I just have a quick question. I tried to read up as much as I could but still haven't figured all of it out. I got the P0420 about a week ago and ever since then I've been getting only about 1-2psi (at best) in 1st gear. I assume that is correlated with the code but just want to make sure there is nothing else wrong with the car. Any idea? 
TIA


----------



## DIAF (Sep 17, 2005)

*Re: (Dave26)*


_Quote, originally posted by *Dave26* »_Hey guys I just have a quick question. I tried to read up as much as I could but still haven't figured all of it out. I got the P0420 about a week ago and ever since then I've been getting only about 1-2psi (at best) in 1st gear. I assume that is correlated with the code but just want to make sure there is nothing else wrong with the car. Any idea? 
TIA

The two issues are completely unrelated. What other codes do you have?


----------



## Demon_S8 (May 25, 2005)

*CEL after 50 miles*

i did the spacer mod to a test pipe installed this weekend. 50 miles out and i got my CEL. expected to see a code for the rear sensor but funny enough it was for the front. i removed the sensor and put it back after clearing the CEL. is this normal or did the 02 sensor have a brain fart or something??. also notice that the cat has now failed the ready ness test?










_Modified by Demon_S8 at 9:47 AM 11-5-2007_


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## bekr83 (May 17, 2006)

*Re: CEL after 50 miles (Demon_S8)*

4,000 miles on my 3" EJ no cell


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## chemicalanarchy (Sep 14, 2007)

*Re: CEL after 50 miles (bekr83)*

First, I got the last motormite 40002 from autozone and was told the 40009 was ILLEGAL and this is in OH with NO emissions. Why is the 40009 illegal?
Next, I was asking 02 sensor and cat questions in the B5 passat forum after my cat got red hot and the car died on the side of the road. I had it towed to the dealer where of course it started right up, but every code was on.
They then tell me the o2 sensor is bad and so is the diverter valve to the tune of $400. I'm no dummy so I go to autozone and have them put the OBD on since I KNOW what a BAD CAT or bad gas does which is get red hot and the stealer wasn't making sense. Their OBD says that it's the second sensor not agreeing with the first one due to THE CAT GOING BAD. Now why would VW lie? Because a new cat under warranty costs them $500 plus labor and they didn't want to do it.
The hell with them as gas mileage and performance were no different and I found this motormite fix thread somehow and I installed it and the 3rd time I drove the car the CEL went OFF!
I then cut the fat heavy useless muffler off and straight piped it and still no CEL.
This thread should be a sticky!


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## vdubN228 (Aug 14, 2006)

*Re: Solution to the rear O2 CEL (kdub790)*

do u think it would work on a 3" dp no cat? cus i hate my check engine light on :mad


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## pope66682 (Jun 12, 2007)

*Re: Solution to the rear O2 CEL (vdubN228)*

Im about to try this cause I got the big R


----------



## snarbles (Aug 19, 2002)

*Re: Solution to the rear O2 CEL (pope66682)*

Just got my first code today with APR 93 + stock modified airbox K/N filter and full turboback Milltek 3" cat -> 2.5" downpipe.
May have to try this if it comes back.


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## turbine1986 (Jul 23, 2005)

*Re: Solution to the rear O2 CEL (snarbles)*

guys i have this cel for a while too and emmisions are here and i replaced the O2 sensor and the cel came back on with this same code







. does this mean my cat is bad???? the old o2 sensor was covered all in white was ****ed. anyone can give me more info?







and oh yea its a 2.0


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## VR6 Guy (May 20, 2008)

*Re: Solution to the rear O2 CEL (deziking)*

Hey gang,
I just wanted to report that I added Wayne's spacer to my stock 99 Jetta VR6. I've had no CEL for over 600 miles and just passed emissions on Saturday - thanks Wayne.
Prior to this, I've replaced O2 sensors several times and replaced the cat once. Last time I took it in, I was told I need a new cat again; that's when I found this forum and Wayne's spacer. 
Thanks much!!!


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## dj givv (May 20, 2005)

*Re: Solution to the rear O2 CEL (VR6 Guy)*

THIS IS FANTASTIC.....just found this thread and it solves my hairpulling issue for the last 6 months! THANKS GUYS!


----------



## DragWag (Sep 22, 2006)

*Re: Solution to the rear O2 CEL (dj givv)*

http://****************.com/smile/emthup.gif I ran across this post last year and just now getting around to posting something on it....
This setup works! I used this setup day one with the installation of an ATP GT2X kit, ATP CAT Delete and other MODS and never, not once ever threw a code!!!


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## mocas (Aug 31, 2005)

*Re: Solution to the rear O2 CEL (DragWag)*

Found this on the net has Pictures and all http://forums.evowned.com/showthread.php?t=3116


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## kevinforgot (Oct 13, 2007)

hmmmm just found out that i have this problem with mine. gonna see what wayne can do for me, hopefully.


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## Too Cold NB1.8T (Apr 18, 2005)

*Re: (kevinforgot)*

Has anyone else had trouble contacting or getting a response from Wayne lately?


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## -Shaun (Aug 29, 2003)

I got a response from him last week. He said about two weeks for the next batch. I'm rolling on expired tags waiting for it.


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## SalMoney (Feb 18, 2008)

I'm going to need to pick up one of these things too. I went to my Vag dealer and they told me the exhaust was tripping my CEL, so they reset it, and sure enough, after about 80 miles, it's on again. So I figure this mod should do the trick.


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## CaseyVR6 (Sep 21, 2005)

*Re: Solution to the rear O2 CEL (kdub790)*

Dude, a picture is worth 1000 words and the pictures aren't there anymore. Any way you could put them back up?


----------



## Mlarivie (Jun 21, 2007)

So you buy 2 the short flat arresters, grind one out to fit the o2, adn the other goes in front, and into the test pipe / cat and thats it?
A poll would help to see what works on the 4Ts' and what works on the 6s'


----------



## trick78skia (Sep 5, 2008)

*Re: (A1.8T)*

for those of you thinking of doing this mod id just like to say one thing from my experience doing it this weekend. ok so i went to autozone and got the "spark plug non-foulers" part number 42002 which supposedly is the longer of the two. ok so the one complaint i have is that the 42002 was an extremely tight fit. maybe if i was doing it again i would start out with the other one first and see how it works out. i only bought the 42002 because that is was the DIY said to start out with. so if i were you i would start out with the other one and see how it goes. other than that it was quick and easy.


----------



## suckapunchdub (Aug 29, 2006)

*Re: (trick78skia)*

anyone know if i do this if ill still get a code if i took my secondary air system out?


----------



## themachasy (Jan 28, 2006)

*Re: (suckapunchdub)*


_Quote, originally posted by *suckapunchdub* »_anyone know if i do this if ill still get a code if i took my secondary air system out?


If you take the SAI setup out you'll get an improper flow code. It has nothing to do with the second O2 sensor.


----------



## suckapunchdub (Aug 29, 2006)

*Re: (themachasy)*

anyone know how to fix this inproper flow code?


----------



## reflected (Apr 6, 2007)

*Re: (suckapunchdub)*


_Quote, originally posted by *suckapunchdub* »_anyone know how to fix this inproper flow code?


----------



## nmjetha (Apr 24, 2009)

*Re: (reflected)*

Does this fix work for P0420 bank 1 code also??????????


----------



## Danofosheezy (Apr 26, 2007)

search "CEL fix" on ebay, you'll find the spacer already modded to fit into the O2 bung, should take care of the CEL, worked for me, or spend the money, get in touch with your local unitronic dealer and get the stage 2 chip, its designed to work with a test pipe


----------



## nmjetha (Apr 24, 2009)

*Re: (Danofosheezy)*

Cool, thanks I might make one unless ebay is cheaper.


----------



## nmjetha (Apr 24, 2009)

*Re: (nmjetha)*

If i only put the Part no. 42002 will that also work?
or i must use the 42009 also? 
thanks


----------



## nmjetha (Apr 24, 2009)

Or is this a combo of the 2 in length and better?
http://cgi.ebay.com/ebaymotors...orted


----------



## pugi03 (Mar 14, 2007)

*Re: Solution to the rear O2 CEL (kdub790)*

cool, i ll try that, but pics plz


----------



## yasuep (Jan 18, 2006)

*Re: Solution to the rear O2 CEL (pugi03)*

Question
The oem cat on my 1.8T AWW had the 2nd o2 sensor bung in the middle of the cat, but the aftermarket Magnaflow direct fit cat, had the bung after the cat. I am curious, when the 2nd o2 sensor location is different ? 
Yasuep


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## yasuep (Jan 18, 2006)

*Re: Solution to the rear O2 CEL (pugi03)*

Question
The oem cat on my 1.8T AWW had the 2nd o2 sensor bung in the middle of the cat, but the aftermarket Magnaflow direct fit cat, had the bung after the cat. I am curious, when the 2nd o2 sensor location is different ? 
Yasuep


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## GLI1.8TSN (Jul 31, 2009)

*A/F gauge*

Id like to know how u connected that gauge to the front o2 sensor? i did my research and found out that the front o2 is a wide band sensor and u hav to weld another bung for the sensor that come with the wide band gauge. Id like to know how u made out?


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## ghent96 (Sep 4, 2009)

Got the dreaded P0420... might try this mod, but I'll look into other problems first.

Installed a magnaflow downpipe after original rusted clean through at the mesh, it's only attached with 3 bolts since one torqued/busted in installation. One 02 sensor is original, and the other is a replacement from original damage. Obviously, I don't think my cat is bad already, but the difference in the 2 sensors or poor seal might be my cause.

I don't think everyone just go doing this mod to solve P0420, as other real issues may exist that should be solved instead of covering them up.


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## 01TornadoWolf (Jun 18, 2009)

ghent96 said:


> Got the dreaded P0420... might try this mod, but I'll look into other problems first.
> 
> Installed a magnaflow downpipe after original rusted clean through at the mesh, it's only attached with 3 bolts since one torqued/busted in installation. One 02 sensor is original, and the other is a replacement from original damage. Obviously, I don't think my cat is bad already, but the difference in the 2 sensors or poor seal might be my cause.
> 
> I don't think everyone just go doing this mod to solve P0420, as other real issues may exist that should be solved instead of covering them up.


so are you now catless or have a high-flow cat?


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## ItsA96 (Dec 14, 2007)

*Has anyone seen or tried this solution?*

http://www.montanafab.com/o2_sim.php for 3 wire O2 sensors 

http://www.montanafab.com/o2_sim_heat.php for 4 wire O2 sensors 

O2simulator.com has similar products but they claim thier products don't work on VW's. 

I have a 96 VR6 OBDII jetta with a partially hollowed out cat. Throwing a CEL for the secondary O2 sensor. Tried the 42DD adapter but it didn't solve the problem. :banghead: 

When researching the 42DD solution I also found threads on how to wire in resistors to solve the problem, but decided to try the adapter in place of hacking up my wiring. Now I can't seem to find info on this solution. 

Any advice?


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## ItsA96 (Dec 14, 2007)

Bump


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## Tate393 (Jun 21, 2011)

kdub790 said:


> Finally... it has arrived!
> *Non-permanent mechanical solution to the rear O2 CEL (P0420)*
> 
> *CEL free for 12,000 miles and counting! (as of 5/23/05)*
> ...


 no pics! i cant see


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## jase421 (May 18, 2012)

Tate393 said:


> no pics! i cant see


Still no pics, any help on this mod would be appreciated.


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## j0nnyr0cket (Dec 18, 2012)

*dealer fix to p0420 out of warranty cat*

i know this thread is pretty much dead but i had the same issue last year and a freind of mine who works for VWoC sent me a tech service bulletin from the tech guys. the stealership can flash your ecu with updated software to open up the window of sensitivity between the front and rear O2 sensors. the same update covers some missfire issues as well. from what i got out of the notice it all came about after VW replaced WAY too many cats under warranty. been almost a year and no CEL, only cost me 1 hr shop rate, not $1000+ for a new cat at owasco. i can send anyone a pdf of the notice if they want


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## Clasen2727 (Apr 4, 2014)

*Having trouble with O2 Sensor*

Hey ok so i have the 2001 Audi TT 1.8t AMU and i am trying to figure out if i have two O2 sensors, and if so where are they.

Also i am having a boost problem and i don't know if it is from the O2 sensor or if its a vacuum leak, though i highly doubt its vacuum cause I have checked all the lines that I can see except for if there is some behind the engine. It has a slight flutter I thought it was the forge DV/BOV but it turned out it wasn't when i took that out and put the stock one in. It idles funny and between 1500 and 2500 the boost doesn't build up and it feels like there is an air flow problem specially when I am shifting, thats why i think it could be the O2 sensor.

If any one has any idea on what to do or what to look for please let me know.


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