# CEL Headaches...what's new? lol



## Slidedude (Dec 18, 2009)

Hi all. New guy here. Thanks in advance for any and all advice.
I have a 2001 V6 Passat, 168,000 mi. I had the timing belt replaced already, about a year ago. 
I noticed a CEL...then a flashing ABS light and three beeps. No communication between the car's computer and the smog check machine, so I can't smog the car. Also, a smoking problem from under the hood. The car sat for about 3 months, then I took it to the shop on Monday. BTW, the battery was completely dead - possibly this is why I got the P1602 DTC below...Here's the codes, and what my mechanic did:
1)DTC's:
18057/P1649 - Powertrain Data Bus: missing message from ABS controller (replaced ABS controller, fault disappeared)
16804/PO420 - Catalyst system: Bank 1 efficiency below threshold
16814/PO430 - Catalyst system: Bank 1 efficiency below threshold
(looks like bad cats)
18010/P1602 Power supply terminal 30: voltage too low (recharged battery, fault disappeared)
16690/PO306 - Cylinder #6 misfire detected (tuneup, new plugs and wires, fault disappeared)
2) Oil leaks? The mechanic replaced the cam chain tensioner gaskets, the cam bore plugs, and the valve cover gaskets on both sides. Oil leak gone.

But yesterday I got a NEW DTC - PO021 - "A" Camshaft Position Actuator Circuit (Bank2). I took it to my mechanic, and he said the guy in his shop must have neglected to "reflash" the ABS...(?)...so he hooked up to my car and entered some numbers, and the fault went away. 
But today the PO0021 came back. Should I take it BACK to the mechanic and request this DTC be cured again? I know I am getting the CEL because of the cats ( I get the PO420 DTC), but I never got the PO021 until the cam chain tensioner gaskets and the cam bore plugs were replaced. Arrrg.
(and I live in CA - don't EVEN get me started on the cost of new cats)
Sorry for the long post, but lordy - I know way too much about the guts of this car, but not EVEN as much as some of you seem to...but I'm really frustrated...


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## O_o (Nov 12, 2009)

*Re: CEL Headaches...what's new? lol (Slidedude)*

First, before replacing your cats (I know that pain), check that the O2 sensors are working properly.
Second, I think your valve timing is off, throwing P0021. I'm not sure if I would take it back, or go somewhere else and forward the bill...


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## Slidedude (Dec 18, 2009)

*Re: CEL Headaches...what's new? lol ()*

Hmmm...OK! Thanks for the reply.
So...the valve timing should have been adjusted during the tune-up procedure? I was under the impression that a tune-up on my car consisted of plugs and wires, and that timing was not part of the tuneup procedure.
Again, bear with me - I'm learning a lot here.....


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## tryin2vw (Dec 30, 2006)

*Re: CEL Headaches...what's new? lol (Slidedude)*


_Quote, originally posted by *Slidedude* »_Hi all. New guy here. Thanks in advance for any and all advice.
I have a 2001 V6 Passat, 168,000 mi. I had the timing belt replaced already, about a year ago. 
I noticed a CEL...then a flashing ABS light and three beeps. No communication between the car's computer and the smog check machine, so I can't smog the car. 


The above are typical symptoms of a failing ABS module. When it fails, it causes all kinds of problems on the OBD2 communications system. Before you change anything else, unplug the ABS module by following the instructions on the modulemasters.com website. Your brakes will still work, but there will not be any ABS type of braking. To really determine the problem, it will be important to scan the car with either a VAG tool or the VAGCOM. Depending on where you are, there may be someone close to help you. The telltale sign is the inability to communicate with the ABS module, but with the inability to talk with the OBD2/Engine Management, it is probably the ABS module.


_Quote, originally posted by *Slidedude* »_Also, a smoking problem from under the hood. The car sat for about 3 months, then I took it to the shop on Monday. BTW, the battery was completely dead - possibly this is why I got the P1602 DTC below...Here's the codes, and what my mechanic did:
1)DTC's:
18057/P1649 - Powertrain Data Bus: missing message from ABS controller (replaced ABS controller, fault disappeared)
16804/PO420 - Catalyst system: Bank 1 efficiency below threshold
16814/PO430 - Catalyst system: Bank 1 efficiency below threshold
(looks like bad cats)
18010/P1602 Power supply terminal 30: voltage too low (recharged battery, fault disappeared)
16690/PO306 - Cylinder #6 misfire detected (tuneup, new plugs and wires, fault disappeared)
2) Oil leaks? The mechanic replaced the cam chain tensioner gaskets, the cam bore plugs, and the valve cover gaskets on both sides. Oil leak gone.

But yesterday I got a NEW DTC - PO021 - "A" Camshaft Position Actuator Circuit (Bank2). I took it to my mechanic, and he said the guy in his shop must have neglected to "reflash" the ABS...(?)...so he hooked up to my car and entered some numbers, and the fault went away. 
But today the PO0021 came back. Should I take it BACK to the mechanic and request this DTC be cured again? I know I am getting the CEL because of the cats ( I get the PO420 DTC), but I never got the PO021 until the cam chain tensioner gaskets and the cam bore plugs were replaced. Arrrg.
(and I live in CA - don't EVEN get me started on the cost of new cats)
Sorry for the long post, but lordy - I know way too much about the guts of this car, but not EVEN as much as some of you seem to...but I'm really frustrated...









The ABS module may be causing some of the above faults. As stated before, try disconnecting the module electrically to see if they go away. 
Also, make sure the CPS is connected and no wire is damaged.


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## O_o (Nov 12, 2009)

*Re: CEL Headaches...what's new? lol (Slidedude)*


_Quote, originally posted by *Slidedude* »_So...the valve timing should have been adjusted during the tune-up procedure?

Er, no. I'm guessing that the cam chain hopped during the tensioner seal replacement operation...


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## tryin2vw (Dec 30, 2006)

*Re: CEL Headaches...what's new? lol ()*


_Quote, originally posted by ** »_
I'm guessing that the cam chain hopped during the tensioner seal replacement operation...

X2. Check the compression in the cylinders. If it is low across the board, then the cam chain slipped a tooth.


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## Slidedude (Dec 18, 2009)

*Re: CEL Headaches...what's new? lol (Slidedude)*

Guys, thanks so much for the extremely valuable suggestions about my car. I know I wrote a bit of a novel, but I was trying to provide enough data to help someone form an opinion. I've made a note of the following items:
1) doublecheck O2 sensors (thanks, !)
2) check operation of ABS controller (however, I did have this replaced already...)
3) doublecheck proper connection of the CPS (thanks, tryin2vw!)
4) verify compression - possible that the cam chain slipped a tooth during the tensioner seal replacment (again, thanks tryin2vw!)
Again, THANK you everyone who replied for your time and knowledge.
Now I just have to cross my fingers and hope my O2 sensors are bad and not my cats. I love living in CA...


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## tryin2vw (Dec 30, 2006)

*Re: CEL Headaches...what's new? lol (Slidedude)*

If the cam chain did slip it could cause unburned fuel to enter the exhaust system, causing the misfire and issue with the cat.


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