I went to move my cold 98 1.8TQMS tonight and it ran a little rough and then the check engine light went on immediately. I live in San Diego and the temp. was about 55 or so. This has never happened before. My car has 4700 miles. Has this happened to anyone? Please Help! Thanks.<br>

I've taken my car into the dealer four (maybe five?) separate times with the malfunction light on. None of them were a big deal, and they were all fixed at no cost to me (still under warranty). The first time was a similar experience to yours, and it required replacement of the "temp sensor", whatever that is. <p>Anyway, get it in to the dealer at your earliest convenience, and they'll fix it. If the light is not blinking, my understanding is that it's no big deal. If it's blinking, though, don't drive it, and get it to the dealer immediately.<p>Rich D.<br>'98.0 A4 2.8QM

One of three things usually happen when the check engine light comes on.<br>1)You topped off the gas when the pump stops you stop<br>2)The engine on while filling up with gas <br>3) Gas cap not on tight enough <p>90% of check engine lights are fuel related unless the light continually blinks it is usually a minor problemm

I live in Los Angeles and I had the same problem immediately after my 5000 service. The head of service at an Audi/Porsche dealership (not where I had the 5k done) explained the problem as the over-sensitivity of ABD 2. My car was dead cold because I had been out of town. I got home late, went out to the garage, started it and immediately turned it off. The next morning when I started it, the check engine light came on. What had changed? <br>1. The car no longer was using the factory break-in oil, it was now using 15/50 Mobil One high performance oil. <br>2. The engine was dry when I did the late night start. I didn't leave the engine on long enough for the check engine light to come on.<br>3. The next morning when I started the car, the check engine signal had already been sent...and only now was I seeing it. <br>4. The Audi/Porsche guy reset the ABD 2 and changed the oil to a lower viscosity 10/40. He said the ABD system is so sensitive that if it feel any roughness, it will do it's job and "predict" a problem. That is the trouble with ABD 2, it is not telling you something is wrong, it is prdicting that something might go wrong. In this case, the slightest roughness caused by slightly thicker oil and dry walls put my ABD on alert and it sent the check engine signal.<br>Modern synthetic oils are very strong and do not break down th way natural or combination oils do. Unless you are increasing turbo heat, Mobil One 5/30 or a 10/40 oil is more than capable.<br>I drive my car very hard and have no over heating of oil temp with the lower viscosity oil. <br>Hope this deals with someone's problem<br>John

You live in LA and the claim was that the 15W-50 oil was somehow too thick and the car sensed this. However, I and lots of other people on the forum use 15W-40 oil all winter, where it actually gets COLD. This 15W-40 is just as thick as your synthetic at cold start, much thicker (more viscous) actually, because of the cold temp. (I have cold started after a couple of days of not running at around ten degrees or so - no engine light).<p>I think that usually the answer lies in the start the car and quickly shut it off routine. The A4 doesn't like this. It seems to flood the engine. Sometimes there are hard starting problems when you try to restart as a result. This is the usual cause of the light on, but I can't say for sure if it was the cause of yours.

What you say makes sense. I gather that the OBD 2 is a nervous little system that will require refinement over the next couple of years. Thanks for your response.<br>John