My CEL lit up this morning and when I plugged in my ODB2 reader it told me that there were no stored codes in the ECU but, that something in the O2 system had failed to run to completion. This was causing the ODB2 reader to tell me there was a pending code and the car to tell me to take it "to the workshop".
Of course, with no actual code there is nothing to clear and no way to turn off the CEL. Throw the damn code already!
Has anyone seen this before or have a suggestion beyond take it to a dealer?
Cheers, Tim
some american car will say o2 sensor not ready...this can take a few hundred miles to "be ready" a batt disconect can cause this. have you had any work done on it lately ?
The CEL actually came on running at the track. The only work done lately is me fixing a oil burning issue due to a mechanical problem. The issue is resolved so its weird that the CEL would occur after the fact but, I suppose it could be a fouled o2 sensor. I think I will take your feedback and run it some more to see if it either clears itself or actually gives a code at some point
thanks
just disconnect the battery for a minute to reset the CEL. Then run the car again and see if it comes back. Maybe a bad sensor.
Let me ask, do you run a non stock exhaust? I have the same problem often times coming off the track and at idle and many times in traffic when I have to sit at idle for a long time. In my case the car is throwing an O2 sensor code but there is nothing there when you take it in to the dealer. I did that a couple of times and then realized it has to do with the exhaust, I run a full B&B system set up with headers and cats. After so many cycles the CEL and visit workshop message go off. I also have a REVO flash that may not be the perfect software upgrade for the exhaust system I run. Your generic ODB2 reader should be able to clear the code. It takes about 5 cycles of the reader to clear it. I finally got tired of having to wait two or three days for the message to clear that I invested the 30 dollars in the Auto one reader and now life is good. As long as it throws the same code ever time I fine. But I read the code just to make sure it is not a different underlying reason everytime it goes on. I neve thought of disconnecting the battery though.
My recommendation to disconnect the battery is only good if you just got the exhaust. If the ECU did not have ample time to adjust. I would not continue to just clear out the CEL error, I would fix what causes it. When you see a CEL error your ECu will try to adjust and make up for whatever caused the CEL to be triggered. I bet you lost power, I bet your B&B system does not make anywhere near the power you'd expect if even more than stock. I have now switched back and forth 3 times between after market and stock exhaust on my 997TT. Spend almost $2k just in labor for the exhaust. Before and after flashing, the CEL is back and no doubt that I am losing power with the after market exhaust. When coming to a stop I can smell unburned fuel fumes. The ECU is trying to enrich the mixture because of the sport cats. So I have a shiny new exhaust at home with less than 500 miles on it and my 997TT sounds like a Prius but the power is without question.
Yes, I have third party exhaust. Like Schwabe, I have a TPC Turbo, which has about 3k of running on it so it is not really new. (perhaps I should update my signature) Getting all the oil out of the system from a failed oil pump, that's new but, the CEL happened after it was fixed. I will try pulling the battery cable next Saturday when I am with the car next.
What are you using to read the code? Can you try Durametric or VAG-COM? They may give you a bit more information.
Thanks for the tip. I don't have access to those readers right now. I don't remember the brand I have but, its a pretty simple code reader with text descriptions and PC support.
UPDATE - I removed the battery cable today for 3 minutes or so and... poof! no more CEL, so far. Let's hope it stays that way.
And because I clearly cannot have a whole day without an issue, after 3 track sessions on the way to the pub today I experienced the dreaded "stuck to the floor clutch pedal" for the first time. I pulled it back up little while later and it seems to be ok now. I bled the brakes this morning, clearly I should have bled the clutch as well. Oh well, next time.
At least the CEL problem is resolved.
