Hey all,<p>A couple weeks ago , I started my 98 Avant up in the morning and the check engine light went on. For the rest of the day, the light was on. The next morning, the light was off and hasn't come back on since. Any similar experiences/advice?<p>Thanks,<br>Rob

<br>Same thing happened to me. Knopf Automotive in Allentown Pa. checked it out and ordered a new ECU. They said AUDI has requested changing the ECU when problems like this occur. They ordered one and I am awaiting the maintenance.

This is pretty common with the OBDII (on-board diagnostics, level 2) system in our A4's. Something as simple as driving with no gas cap can turn on the check engine light. In the case of a missing gas cap, others on the board have replaced the missing cap and then the light will go out a few days later.<p>Tony O. suggested that Audi will replace the entire ECU if your check engine light stays on. I find that hard to believe as the ECU's sell for something like $1000. Quite a few other board members have had their check engine lights come on for various reasons, but I doubt they all received new ECU's.<p>I'd have your dealer look into it, only they will know the exact cause of your "check engine" light lighting. Hope this helps,<p>Andy Hedin<br>'97 A4 1.8Tqms, Wett 1.0 Bar Chip, ABT Filter, Euro Headlights with<br>PIAA SuperWhite's, A!AvantGarde Grill, Smoked Side-Markers,<br>Clear Corner-Markers, Tint