I searched the previous posts and have not found anything regarding this one. Has anyone dealt with it? 2000 1.8T Quatro with 75K Runs flawless but this came up after CEL

 

Maybe some will be more help but my service manual says it can either be ecm harness shorts or a bad resistor in the ECU (It says something about there being a required resistor in the ECU for communication that needs a resistance between 62 and 70 ohms. It says to check that measure between the 58 and 60 terminals on the ecu, but im not sure. If it isnt between 62 and 70 then the computer is bad. I dont have a diagram of the pinout of the ecu so maybe someone else might have that.

It says the second possiblilty is a bad harness and it says to check for a short betweeen the harness, connect a meter to the same pins but this time on the harness instead of the computer and check for infinite resitance (so you should have no connection there at all). If there is a connection there is a short in wiring somewhere.

Hopefully someone else might be able to shed a little more light on this...

 

Thanks for the information, at least I now have an idea of where to start. I guess I should get a Bently's manual too. Is that the service manual you were refering to? Browsing the forum, I think I have been very lucky to have no trouble at all with the car for 75K, and hope this is not a sign of more problems to come.

 

Yeah thats what I was using. Its a pretty good all around manual, but other ones have their advantages too. I like chiltons wiring diagrams better (although its limited to how many it has), and some other ones have better pictures. This does seem to be the best overall i think though.