[chlaird]

I've got a 2002 mkiv Jetta, 2.0l, 118k miles. It took a little while but it's running great right now, no problems I can notice. The issue is that the Check Engine Light never goes away. We clear it, it comes back, ad infinitum. It's out of inspection, so I've gotta get this fixed before I can get inspected and really get my baby back on the road.

To be clear, here are the main symptoms:
- The CEL always comes back. We clear it, and always at around 50-60 miles later it comes back. Every time.

- Every time I drive, the EPC light comes on about 15 minutes in, stays for about 7 minutes, then shuts off. Every time.


I'm a pretty broke college kid, so I can't afford the real VAG system, but I bought a cable on amazon and used VCDS-lite. Here are the results.


VCDS-Lite Version: Release 1.2
Tuesday, 26 March 2013, 18:01:02.
Chassis Type: 9M - VW Jetta IV
Scan: 01,02,03,08,09,15,16,17,19,22,29,35,36,37,39,46,47 ,55,56,57,75,76

-------------------------------------------------------------------------------
Address 01: Engine Labels: 06A-906-032-AZG.LBL
Controller: 06A 906 032 FP
Component: 2.0l R4/2V 4072
Coding: 00003
Shop #: WSC 00066

8 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent

16687 - Cylinder 3 Misfire Detected
P0303 - 35-10 - Please Register/Activate - Intermittent

16686 - Cylinder 2 Misfire Detected
P0302 - 35-10 - Please Register/Activate - Intermittent

17560 - Long Term Fuel Trim Additive Air; Bank 1; Range 2: System too Lean
P1152 - 35-10 - - - Intermittent

17549 - Load Calculation Cross Check: Implausible Value
P1141 - 35-10 - Please Register/Activate - Intermittent

16955 - Brake Light Switch (F): Implausible Signal
P0571 - 35-10 - Please Register/Activate - Intermittent

16804 - Catalyst System; Bank 1: Efficiency Below Threshold
P0420 - 35-00 - -

17573 - Shareware Version. To Decode all DTCs
P1165 - 35-10 - Please Register/Activate - Intermittent

Readiness: 0000 0000


VCDS-Lite Version: Release 1.2
Tuesday, 26 March 2013, 18:04:52.
Control Module Part Number: 1C0 962 258 AC
Component and/or Version: 21 Zentr.Verriegel. 0003
Software Coding: 00018

2 Faults Found:
00931 - Locking Module for Central Locking; Rear Right (F223)
54-10 - Incorrectly Equipped - Intermittent
01044 - Shareware Version. To Decode all DTCs
35-00 - Please Register/Activate



My dad has a handheld OBDII scanner. When I scan with that, these are my results:

P0420- catalyst system efficiency below threshold
P0172- system too rich




HERE IS WHAT THE 2 MECHANICS DID BEFORE GIVING UP
1. Swapped the front 02 sensor (twice)
2. Swapped the rear 02 sensor
3. Swapped the catalytic converter
4. Swapped the MAF (twice)
5. Closed leaks in the rear exhaust system pre/post cat
6. Checked for vaccuum leaks in engine (none found)

HERE IS WHAT I HAVE DONE
1. Flushed coolant system (fixed the heating, unclogged heater core)
2. New coolant temp sensor
3. New thermostat (190 degree from autozone)
4. Removed/reinstalled the coil pack to check from cracks



I'm at my absolute whits end, the mechanics have given up, does anyone here know the secret that has been eluding me??

 

[Jim @ APR]

Have you inspected the coil pack harness? Pull the ecu and inspect for condensation/corrosion as well. Any software on the vehicle? Mods?

 

[chlaird]

Have you inspected the coil pack harness? Pull the ecu and inspect for condensation/corrosion as well. Any software on the vehicle? Mods?

In order of what you said:

When I pulled the coil pack, I believe I inspected the harness. I'm not 100% sure, but I'm usually pretty careful to check stuff like that. I'll check again soon to be safe.

I can do that, but is there any chance of me messing something up? Should I pull the battery first? And I'm assuming I get to it by removing the wipers, removing the plastic shield beneath that, then just unscrew it and slide it out? I've never looked at the ECU before, but I'm familiar with the area because I pulled out the wiper motor to unseize it.

As for mods, I don't think so. I bought the car used 15k miles ago, but I have no reason to believe it was modded or chipped. Any way to check that?

 

[Jim @ APR]

http://www.goapr.com/support/ecu_tt_golf_gti_jetta.pdf

If there is software, there will be a chip soldered to the board. My main focus would be on the condensation/corrosion possibility.

 

[chlaird]

http://www.goapr.com/support/ecu_tt_golf_gti_jetta.pdf

If there is software, there will be a chip soldered to the board. My main focus would be on the condensation/corrosion possibility.

I find myself utterly impressed at how informative that link was. Thanks! I'll go check all that now

 

[Jim @ APR]

I find myself utterly impressed at how informative that link was. Thanks! I'll go check all that now

No problem. It's what we do.

 

[pow3r hour]

How does the car run? What does it idle at? Brake light switch will solve your epc light, but Im sure thats the least of your worries. Id also re check yourself for vacume leaks esepcially the pcv system. Pcv valve itself could also be bad.

 

[chlaird]

How does the car run? What does it idle at? Brake light switch will solve your epc light, but Im sure thats the least of your worries. Id also re check yourself for vacume leaks esepcially the pcv system. Pcv valve itself could also be bad.

In order:

1. The car seems to run great. Reliable, doesn't stall out, hasn't stalled on start since the new MAF went in. No noticable problems while driving at all (at least to me).
2. I'll check the idle in the morning. I'm not sure what it's at, but it seems stable. It does get a little louder and quieter if I just let it sit, but just a little. It doesn't idle rough during that. (I should note, my brother put a new exhaust on it because the old one rusted through, so it's louder than a normal jetta, so I can clearly hear the changes in idle volume).
3. I have no idea what a pvc system or pvc valve are. I'll look those up now and investigate them tomorrow.

 

[slayer450]

In order:

1. The car seems to run great. Reliable, doesn't stall out, hasn't stalled on start since the new MAF went in. No noticable problems while driving at all (at least to me).
2. I'll check the idle in the morning. I'm not sure what it's at, but it seems stable. It does get a little louder and quieter if I just let it sit, but just a little. It doesn't idle rough during that. (I should note, my brother put a new exhaust on it because the old one rusted through, so it's louder than a normal jetta, so I can clearly hear the changes in idle volume).
3. I have no idea what a pvc system or pvc valve are. I'll look those up now and investigate them tomorrow.

Sounds like you have an idle surge, it's not always that notice. Good probability that you have a vacuum leak. Can be anything from a pin hole in a vacuum line to a bad pcv valve to a leaking intake gasket.

Pcv stands for positive crankcase ventilation. It's a system to make sure you don't get excessive pressure in the bottom end. It pulls are out of the crankcase and puts it into your intake, it's why you're intake always has that black sludge in it.

Sent from my R800i using Tapatalk 2

 

[DasBohan]

easiest way to find your leak because as stated it could be a pin hole, or hairline crack; get some hand soap and a little water in a spray bottle, and with the car running, lather up your vac lines. Start at the pcv hose, it Y's off the intake. Your pcv valve attaches to your main intake tube. You can pull the clips off and inspect yourself, check for built up oil residue that may be causing malfunction.

 

[chlaird]

I just sprayed down the coil pack, right where the wires plug in, with a bottle of water. Car was running, and a few sprays right where they plug in caused an arc/spark on the bottom of the 4 plugs.

Does that mean my coil pack is bad, or that the wires need replacing?

 

[KiDGiB]

Sounds like they are working. What your supposed to do is spray your vacuum lines to see if any air is leaking and look for it to bubble.

 

[pow3r hour]

No, that doesnt mean they are working, you should not get arcing, everything should be sealed. Its a good test to do to check for a cracked coilpack. Id take it off and inspect it further.

 

[chlaird]

No, that doesnt mean they are working, you should not get arcing, everything should be sealed. Its a good test to do to check for a cracked coilpack. Id take it off and inspect it further.

Thank you, I'll pull it off tomorrow and look for cracks. I talked to my friend and he said it could also be that the wire is cracked or needs to be replaced right at the end. Would that make sense, or is the coil pack definitely at fault when it arcs like that?

Sounds like they are working. What your supposed to do is spray your vacuum lines to see if any air is leaking and look for it to bubble.

I also did that to check for vacuum leaks. I didn't see any bubbling at all. I feel like I can hear a faint hissing sound, but it gets louder the closer my ear is to the "air intake box" or whatever it's called, and it sounds like it's directly from the box, not a hose.

 

[Jim @ APR]

I thought you already checked the harness? That was the very first thing I suggested you look at. Regardless, I hope you get it sorted out.

 

[chlaird]

I thought you already checked the harness? That was the very first thing I suggested you look at. Regardless, I hope you get it sorted out.

You are correct Jim, I did already check the harness. Nothing on the harness looks corroded, and I pulled the entire coil pack out and found no cracks. However, I do take into account the fact that if I can't figure out what the hell is wrong with my car, then I may have made some mistakes. So I rechecked. You can never be too safe And since I saw an arc, I'm assuming I did miss something. I'm just not entirely sure what the arc means yet

 

[blackhawksfan]

I have an 01 Jetta with the exact same problem. My only code was the p0420. 4 different mechanics later and my check engine light is still on. Cat was replaced and the light stayed off for a few months. Now it is back on again. Have you had to go through emissions yet?