I just bought a used 2001 A4 1.8T this monday and the CEL came on while I was driving back from Chicago. I have checked the gas cap etc. I have also taken the car to 2 mechanics [one of them specializes in Audi/Saab] and their scanners have been unable to communicate with the ECU / ECM in the car. The specialist mechanic also mentioned he was unable to read the Airbag/Transmission ECM.

I am wondering if I should just get an ECM off ebay motors and have them replace it, or try to figure out what is wrong. If someone has had experience with this sort of thing or might be able to venture a good guess as to what might be an issue I would really appreciate it.

I am a grad student at UIUC and I would like to get this done without spending hundreds of dollars. I do not have experience working with automobiles but I am a quick study. So if it is worth it getting a service manual and some tools and then trying to do this myself, I would be willing to give it a shot.

 

Bump!

 

bring it to any autozone/ advanced auto parts / pep boys or similar store and borrow their scanner. if that scanner doesnt work you have a problem with the OBD2 connector probably. the car runs normaly with the exception of the CEL correct? that means the ECU is atleast mostly working and something should be able to contact it.

also what type of scanners did the mechanics use? VAG-specific, or just a generic OBDII? i know VAG-COM software says that if you try to scan the airbag module with the wrong signal or something you can damage it or possibly set off the airbags, so i would be careful when scanning those blocks. also if your car is a manual, you dont have a transmission control module i believe so you wouldnt be able to scan it.

 

Not sure if this was for older models or not, but I remember seeing that some aftermarket radios/adapters can actually short the "K line" that OBD2 communicates on.

 

Hmm This does have an aftermarket dvd player installed. Thanks for that info.
In addition autozone and 2 other mechanics were unable to communicate with a bunch of different scanners, the car is auto + triptronic.