# Check Engine Light - 16486 and 00518



## 79909 (Dec 30, 2002)

Hey guys my car has been out of commission for a few weeks we found out it was the ECU but a shop i brought it to thought it was the MAF sensor using there crappy generic ODB-II scanner they put in a new MAF and it was still the same so after a replacement ECU worked they put back my old MAF back in and it turns out later when driving home i get a CEL and i thought maybe its from swapping out so many parts including ECU. So i cleared it and drove a bit and CEL came back and heres what it was.
Chassis Type: 1H - A3 VW Golf III
Scan: 01,02,03,08,12,15,25,56
Address 01 ------------------------------------------------------------
Controller: 037 906 259 R
Component: MOTRONIC M5.9	AT V01
Coding: 00001
Shop #: WSC 00066
1 Faults Found:
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-00 - -
Readiness: 0110 0101
Address 02 -------------------------------------------------------------
Controller: 01M 927 733 DL
Component: AG4 Getriebe 01M	3531
Coding: 00000
Shop #: WSC 00000
1 Faults Found:
00518 - Throttle Position Sensor (G69)
16-10 - Signal Outside Specifications - Intermittent
Skipping Address 15-Airbags
End ---------------------------------------------------------
As for the first error do you think i should replace the sensor or could there be a vacuum leak of some sort? my second question is about the 00518 - Throttle Position Sensor error do you think that is caused by the first error? do you think it will clear up after replacing the MAF sensor ?




_Modified by kewlrichie at 1:16 PM 1-5-2010_


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## Dana @ Ross-Tech (Sep 15, 2009)

*Re: Check Engine Light - 16486 and 00518 (kewlrichie)*

Hard to say. Why and how was the original Ecm faulty?
Was the fault cleared out of the Tcm after the work was done? It could be old (Intermittent) Or possibly the early signs of a TM problem.
Try a TBA and see if it completes properly.


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## 79909 (Dec 30, 2002)

*Re: Check Engine Light - 16486 and 00518 (Dana @ Ross-Tech)*

im not 100% sure how the ECU was faulty but the car would barely start with it and when we replaced it with a used one it started right up.
As for a TBA I am assuming you mean Throttle Body Alignment I have the info for that saved on my laptop I am going to try that now. So should I do that and clear the codes once more and see what happens on the way home from work?


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## Dana @ Ross-Tech (Sep 15, 2009)

*Re: Check Engine Light - 16486 and 00518 (kewlrichie)*

Yes, but I would expect the MAF fault to return. Clear the faults before the TBA.


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## 79909 (Dec 30, 2002)

*Re: Check Engine Light - 16486 and 00518 (Dana @ Ross-Tech)*

Thanks Dana for the replies I appreciate it
I went out and did the TBA (before seeing your second post) using "Procedure for performing a Throttle Body Alignment on Cable-Throttle Cars" i went to 098 and before even clicking Basic Settings i got...
4.360v - 3.540v - Idle - ERROR
then when clicking Basic Settings i received
ERROR - Group 098 - Not - Available 
I just read your reply should i have cleared the CEL before trying to perform this?
I also disconnected and reconnected the connectors for the throttle body and MAF just for good measure



_Modified by kewlrichie at 1:58 PM 1-5-2010_


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## 79909 (Dec 30, 2002)

*Re: Check Engine Light - 16486 and 00518 (kewlrichie)*

ok so i cleared the codes and tried the TBA and still cant do the adaption from mess.block 098 same errors as above.
So after reading the "test conditions" for TBA i think some of my conditions aren't met. It is now 30 F over here in NYC so i think i will give it another try when i get home from work the car will be all warmed up and im guessing i will get another CEL so i'll clear that and try again. I will also check my battery to make sure im getting at least 11.5v using a multimeter.


_Modified by kewlrichie at 2:15 PM 1-5-2010_


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## Dana @ Ross-Tech (Sep 15, 2009)

*Re: Check Engine Light - 16486 and 00518 (kewlrichie)*

Yes, sounds good. Normal operating temp, Properly charged battery, Drls off if possible, etc. 
If it still goes to error, it might need removed and cleaned using Throttle Body cleaner (3M is the best IMO) and a toothbrush.
-remove the unit from the manifold (do not disassemble it in any way, just 4 bolts, cable, wiring connector and hose)
-hold the electrical portion up so cleaner does not go inside the electronic side
-clean it with the throttle plate fully open to get all of the carbon out
I would lay it on top of the manifold and plug it in and try to adapt while watching the movement. It should complete properly.
If you don't have a garage, you may not want to do this outside in this weather.


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## 79909 (Dec 30, 2002)

*Re: Check Engine Light - 16486 and 00518 (Dana @ Ross-Tech)*

ok i drove home car was warmed up check engine light was back on as soon as i got into the car so when i got back i cleared it and tried the TBA again and it gave the same error. checked the battery and my multimeter says i am getting 12.78v with the car off.
I also tried to do the TCM reset following the ross-tech guides to see if that will fix the 00518 - Throttle Position Sensor (G69) problem. I'll check tomorrow what codes come up again.
when the car was barely working and we were testing out of a few things trying to get it working, i bought a used throttle body from a 98+ car (because i have a 99 which needs the extra breather hose) and thats on there now. So i still have my original throttle body, which i took off awhile back to give it a good cleaning a few months back. I think if worst comes to worst i could try and swap that one back in if the cleaning doesn't work or maybe not even bother with the cleaning? probably should of cleaned the used one real good before they installed it








The worst part is that my inspection is expired now (Jan 2010) so i need to figure out this check engine light problem ASAP. btw: Dana would you know what readiness codes need to be passed to pass NY inspection ? all of them? 0000 0000 ?



_Modified by kewlrichie at 12:46 AM 1-6-2010_


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## Dana @ Ross-Tech (Sep 15, 2009)

*Re: Check Engine Light - 16486 and 00518 (kewlrichie)*

I do not know what the Readiness requirements are for NY state IM testing.


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## 79909 (Dec 30, 2002)

*Re: Check Engine Light - 16486 and 00518 (Dana @ Ross-Tech)*

Hey Dana I cleaned my old throttle body and put it on and cleared the DTC's and the TBA worked!!. I Also reset the TCM using the Ross-tech guide...000, go, hold pedal for 3 seconds, then back and release. Still got the same DTC's as on my first post. Is there any other kind of reset i could do with the vag-com? for the TCM to try and clear up the 00518?
I really hope there isn't anything wrong with this ECU. It's reading the codes fine, clearing and there coming back pretty quick so I'm assuming the ECU is doing it's job properly.
I should probably get a new MAF sensor to try and fix that 16486?
or should i test the sensor using this method http://faculty.ccp.edu/faculty...g.htm or could I do it better with the Vag-com
Thanks











_Modified by kewlrichie at 11:11 PM 1-6-2010_


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## 79909 (Dec 30, 2002)

So I changed the MAF and cleared the codes and it seemed like the 00518 went away but I'm still getting the 16486 - Mass Air Flow Sensor (G70): Signal too Low...what else could I try ?


_Modified by kewlrichie at 11:32 PM 1-11-2010_


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## Dana @ Ross-Tech (Sep 15, 2009)

*Re: (kewlrichie)*

Sorry I missed your last post. If the MAF was the correct one and good / or new, check the wiring from the MAF connector to the Ecm.


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## 79909 (Dec 30, 2002)

I got a used one from someone on here it was the same part number 037 906 461 C. Now how would I go about checking the wiring from the maf to the ecu ? Could I use dans reeds link above to check ? Or should I just check for continuity with a multimeter for each of those four wires??
And let's say a wire is faulty what would I have to do to fix it? Get a new wiring harness or try and run a new wire? 
I'm good with soldering so that's a possibility if needed


_Modified by kewlrichie at 1:25 AM 1-12-2010_


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## 79909 (Dec 30, 2002)

*Re: (kewlrichie)*

hmm ok so it wasn't that cold today and i had a chance to look around and i think i might of found something. The PCV valve (crankcase pressure regulating valve) seems to be split on the side and it looks like someone tried to epoxy it back together im assuming the shop did this without me knowing because i definitely didn't. Ive been hearing that a vacuum leak could cause the 16486 DTC so im wondering now if this could be the problem? i hope so

















and also does this MAF look ok to you, my original one the little flap was broken in half so im definitely sure my old MAF wasn't in good shape but if you look at this one i have pics below it seems that one of those little flaps moves very easily and depending which way i have the MAF (its bending down now) and if i blow into it stays in the middle. just wondering if thats normal for that one flap to be flimsy like that?












_Modified by kewlrichie at 3:50 PM 1-12-2010_


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## bahnblitz (Jan 18, 2002)

*Re: (kewlrichie)*

Looks to be MAF related
The MAF "hot wire" should not bend or be broken. If yours bends you have problems!!


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## 79909 (Dec 30, 2002)

*Re: (bahnblitz)*


_Quote, originally posted by *bahnblitz* »_Looks to be MAF related 
The MAF "hot wire" should not bend or be broken. If yours bends you have problems!!


thanks for the reply
hmm interesting...but the thing is my old MAF which had one of those "hot wires" broken in half and that never through a CEL so im wondering how that would cause the issue...
So im sort of learning towards that being the split PCV breather valve on the side and is definitely leaking air it might be causing the CEL...


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## bahnblitz (Jan 18, 2002)

*Re: (kewlrichie)*


_Quote, originally posted by *kewlrichie* »_
thanks for the reply
hmm interesting...but the thing is my old MAF which had one of those "hot wires" broken in half and that never through a CEL so im wondering how that would cause the issue...
So im sort of learning towards that being the split PCV breather valve on the side and is definitely leaking air it might be causing the CEL...











The MAF only has one hot wire. . . It could be broken and still work or work intermittently. You can check its function using the measuring blocks. Go to display group 15 and 16. You can not do any tests to the MAF itself (i.e. resistance testing) 

You can check for suspected air leaks with a spray bottle of soapy water or a can of ether/starting fluid if you believe you have a vacuum leak. Spray it in the suspected area and watch for air bubbles or a slight increase in idle speed


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## 79909 (Dec 30, 2002)

*Re: (bahnblitz)*

So all those little things in the MAF are suppose to be all stiff and non movable or that last one is suppose to be flimsy ? Mine was split in a half and never got a CEL and the guy i bought this one from said it was working fine for him also no CEL. If i touch that little "flap" with my hand and bring it back up it will stay in the middle i just sort of made it go down gently to show it guys that it moves.
So what am I looking for if I look at the measuring blocks for 15 and 16 ? Am I looking for a certain number if somethings lower or higher ? 
As for the leak i think its pretty noticeable that thing is leaking air theres a huge crack on the side and you can lift it with your hand and you can see inside. I got valve cover gasket replaced and also bought that small rubber grommet that sits under the PCV valve and im guessing that the guy tried to put the rubber grommet on the PCV valve first then tried to push down real hard to get it into the valve cover and cracked it and tried epoxying back together. Now the real question is if i have a big leak in the PCV like that could that cause the MAF error code im getting?




_Modified by kewlrichie at 3:44 PM 1-14-2010_


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## bahnblitz (Jan 18, 2002)

*Re: (kewlrichie)*

A vacuum leak could cause your problem but other things can cause it too.
There is not one definite answer with out testing and finding the actual solution.
Do you have a Bentley Manual? If not buy one ASAP, it's worth it's weight in GOLD. They have all the procedures to check the MAF and related wiring.
If you can open the piece on the valve cover with your hand you have a vacuum leak!! Oil attacks plastic and rubber so it could be a combination of too much force from the previous owner and just wear and tear.


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## bahnblitz (Jan 18, 2002)

*Re: (bahnblitz)*

DO NOT TOUCH THE HOT WIRE!!!!!!!!


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## bahnblitz (Jan 18, 2002)

*Re: (bahnblitz)*

Or how about this. . . fix the vacuum leaks first because you need to fix them anyway and see if the codes clear.
In the two measure blocks I stated above you should be able to read the grams/second of air passing the hotwire in the Maf about 2-4 g/second at idle and 80 g/s at WOT. If it is a lot less, bad MAF.
The other measuring block should be the fuel trims (032 I believe)
One is ADD (additive fuel trim) if it is higher than 2% then BINGO, you have a vac. leak
http://www.ross-tech.com/vag-c....html


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## Dana @ Ross-Tech (Sep 15, 2009)

*Re: (bahnblitz)*

Also look at MB 000 at idle, it will display 10 fields. Focus on the second field for MAF sensor readings, an average value of 40-44 should be present providing that the mentioned vacuum leak is fixed and the MAF is good. As bahnblitz mentioned MAF readings can also be found in several other locations and he mentioned the specifications for MB 15.
Did you reinstall the new MAF that the repair shop sold you in the beginning with the Ecm replacement? If so is it the same part number as your original?
It might not hurt to call the repair shop for a list of codes they had prior to the diagnosis. If the same fault was stored I would check the wiring and connector closely.
http://wiki.ross-tech.com/inde...00258


_Modified by Dana @ Ross-Tech at 2:23 AM 1-16-2010_


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## 79909 (Dec 30, 2002)

*Re: (Dana @ Ross-Tech)*

ok i replaced the PCV valve and im pretty convinced the shop i brought it to for the first repair definitely broke the PCV and tried to epoxy it back together checkout this pic..









So after changing that i cleared the fault codes and drove for a little and the light stayed off and parked came back like 10mins later i seen the check engine light again then it went away then came right back a second later. I thought i fixed it for a second anyways i took some vag-com readings so here are some pics...
here is a reading at idle with the replacement used MAF i bought from someone on the vortex. This pic is at its lowest 2.84 g/s it would go back and forth from that to like real low 3's like 3.12 g/s something like that








and heres it with the rpms at 2400








and now here is the old MAF thats cracked on the outside housing and one of those little fins inside are broken. Funny part is it never gave me a CEL before so i just put it back in there just for the hell of it and i still got a check engine light anyways.








So could it be both the MAFs or wiring maybe?

_Quote, originally posted by *Dana @ Ross-Tech* »_Also look at MB 000 at idle, it will display 10 fields. Focus on the second field for MAF sensor readings, an average value of 40-44 should be present providing that the mentioned vacuum leak is fixed and the MAF is good.

my second field seems to not be in that 40-44 range so is the MAF bad or could the wiring do something like that also?
oh BTW i couldnt find the MB that had "ADD" for the fuel trim maybe my super old vag-com software doesn't do that?
Thanks again for all the help and replies, let me know if there's anything else i should be testing for to get rid of this damn check engine light so i can get a inspection that's already a month expired











_Modified by kewlrichie at 11:46 PM 2-1-2010_


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## bahnblitz (Jan 18, 2002)

*Re: (kewlrichie)*

The one MAF on top seems a little off. Less than 8 g/s at 2,400 RPM. Should be up like 9-15 g/s.
Did you ever get a Bentley manual? They tell you how to check the MAF wiring with a voltmeter, very easy.
Could be tow bad mafs or the wiring is cracked/damaged (very common)


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## 79909 (Dec 30, 2002)

*Re: (bahnblitz)*


_Quote, originally posted by *bahnblitz* »_The one MAF on top seems a little off. Less than 8 g/s at 2,400 RPM. Should be up like 9-15 g/s.
Did you ever get a Bentley manual? They tell you how to check the MAF wiring with a voltmeter, very easy.
Could be tow bad mafs or the wiring is cracked/damaged (very common) 


Ive always had a bentley. I didnt see the part about testing the MAF but i didnt test the MAF this way using Dans Reeds instructions http://faculty.ccp.edu/faculty...g.htm it was a month or two ago so i dont remember the readings. so according to this guide being that i have a OBDII the engine should be running during the first test right?
If the wiring is bad thats going to be a b*tch to figure out no? i would have to take apart that whole harness check the wires one by one i guess? i know how to use a multimeter and check for continuity but im still abit unsure about this...if anyone can shed some light on this it would be great


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## bahnblitz (Jan 18, 2002)

*Re: (kewlrichie)*


_Quote, originally posted by *kewlrichie* »_

Ive always had a bentley. I didnt see the part about testing the MAF but i didnt test the MAF this way using Dans Reeds instructions http://faculty.ccp.edu/faculty...g.htm it was a month or two ago so i dont remember the readings. so according to this guide being that i have a OBDII the engine should be running during the first test right?
If the wiring is bad thats going to be a b*tch to figure out no? i would have to take apart that whole harness check the wires one by one i guess? i know how to use a multimeter and check for continuity but im still abit unsure about this...if anyone can shed some light on this it would be great




The Bentley has clear test procedures, so does Dan Reed. You have to do one or the other. They are both extremely easy. There is no need to take apart any wiring.
I would say sit down and re read the Bentley . . it has all the info you need to diagnose the car. 
If you can check continuity and you know how to measure voltage with a voltmeter than it is extremely easy.


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## 79909 (Dec 30, 2002)

*Re: (bahnblitz)*

ok I was able to get some time after work to do some MAF testing/checking. I wanted to get it done before we get all this snow tomorrow. So i followed Dan Reed's guide at http://faculty.ccp.edu/faculty...g.htm
So here are my pics and findings.
This is the volt measurement from pin 3 with the car turned ON but engine OFF








This is the volt measurement from pin 3 with the car turned ON and turned the engine ON after reading if you have a ODBII should be on. I just did both measurements for the hell of it. 13.89v looks ok i think








Now with the car OFF this is the ohm measurement for pin 1








Now with the car OFF still this is the ohm measurement for pin 2








Looks a bit high on both those pins the guides says 
_Quote »_You should get LESS then 3-4 ohms on BOTH pins. If you get MORE then 3-4 ohms check the harness for breaks or opens, or the connector at the ECU for damage. 

Now here is the backprobe from pin 4 while the car is running








which looks very high?? i thought for a second my multimeter was screwed up or i had a wrong setting...so i went and tested the battery for good measure and it was 12-13volts so i dont know about this reading looks very high or am i reading this wrong. The guide says

_Quote »_Voltage at IDLE should be around .9 volts DC.


I haven't checked the pins in the ECU yet. But i remember looking at the quickly when i received it and didn't notice anything wrong. now im wondering if there's was something wrong with the ECU or maybe a pin or something and i bought it damaged..really hope not









So any info would help thanks again for everyone's help




_Modified by kewlrichie at 6:33 PM 2-9-2010_


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## 79909 (Dec 30, 2002)

bump


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## 79909 (Dec 30, 2002)

anyone with anymore info?


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## vwemporium (May 27, 2002)

*Re: (kewlrichie)*

Did you get the TB error in 01-04-098 to complete a ADP or is it still in error?
Did you fix the Elmer's glue repair breather for the VC to intake boot?
This would be a good idea.
You should also perform a default.
Each item in between a key cycle.
01-02-05
01-10-00 save data default.
01-11- 01283 login
01-07- same data.
01-04-098 test and verify maybe clean TB massage at idle offset backwards against spring before idle.
The TB must go backwards in order to move forward with the ADP for 04 basics. The ADP in basics is different then the one the ECU performs on its own from an already learned position.
Best,
Jack


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## 79909 (Dec 30, 2002)

hey jack thanks for your reply
the TB completed the ADP fine and the PCV was fixed with the good one the only problem is the 16486 low voltage that i cant seem to get off. I did some multimeter testing and pin 4 it suppose to show .9volts but im only getting 171.0 MILLIVOLTS so is like .1volts only which would explain the error. I checked the wires at the plug and it seems good but i haven't unwrapped the harness or unplugged it from the ECU to check the pins or anything because its been too cold



_Modified by kewlrichie at 8:45 AM 2-23-2010_


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## vwemporium (May 27, 2002)

*Re: (kewlrichie)*

Well get on the snow suit buddy.


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## 79909 (Dec 30, 2002)

*Re: (vwemporium)*


_Quote, originally posted by *vwemporium* »_Well get on the snow suit buddy.









ahh damn you fooled me i thought this was helpful info. thanks anyways
bump!


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## Dana @ Ross-Tech (Sep 15, 2009)

*Re: (kewlrichie)*

Since you have already checked the wiring, and not found any excessive resistance or connector issues...The most likely faulty component is the MAF. Replacing it with the correct new one would be the best option at this point.
The ECM could be faulty..but that is the least likely failed component. Your original shop diagnosed a faulty MAF and found the original ECM was bad. It is very possible the vehicle had two problems, the first main problem was corrected and the car runs now. We don't know how / why the first ECM was bad. Surely if the second (currently installed) one has failed, some extensive testing and diagnosing needs to be done.


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## 79909 (Dec 30, 2002)

thanks for the reply Dana
I only did that multimeter testing from the MAF plug and didnt check the harness or ECU yet. 
I do want to unplug the harness from the ECU and check for continuity from MAF plug to the ECU side to see if there is a break or not and maybe even check the ECU make sure none of the pins are bent or something. 
Now as for getting a new MAF do you think that could be causing the problem of not getting .9volts back to the ECU from pin 4? im getting about .1volt from my testings above. The weird part is that i never had a CEL light before with my old MAF until my ECU went bad. I also tried my old one and this used one i got off of someone one on here. The only thing that makes me think its the wiring is that i believe what caused the problem in the first place was that my rain tray was clogged with crap and i think it filled up with the water and sorted out my ECU which maybe fried one of my MAF wires? could that happen?
now that i think about it if the MAF is getting normal 12v in from pin 3 and its not returning the right .9 voltage back to the ECU. Its hard for me to think that both those MAFs are bad because my original one never threw a CEL but i guess with the ECU shorting out or whatever happened to that could of damaged it of course. With the replacement used MAF i guess theres a chance it can be bad also. Im leaning towards thinking that the bad ECU might of ruined the MAF wiring. So im going to do some more poking around and see what readings i come up with testing from the connector all to way up to the ECU connector.
...this is very frustrating











_Modified by kewlrichie at 12:30 PM 2-25-2010_


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