Just have a emission test done at Midas, and they told me that there is no signal from onboard diagnostic computer system

can anyone help?
thanks a lot

Here is my story. I had the same problem. Failed Illinois emissions. Took it to Audi for this problem. They replaced the Airbag computer and now the OBD works fine and it passed state required emissions. Cost was 1200.00 The computer was 700 plus 5 hours labor @ 102.00/hour. Seems the airbag computer is under the radio and a pain to get at.
Now for the rest of the story and the bad news for me. The airbag light is now ON. It wasn't before the computer was replaced. The airbag computer is reporting 7 sensor/airbag faults. Most are coming from the seat sensors and the side(in the seat) airbag igniters. They attempted to fix some the faults when the computer was replaced but ran out of time that day. I've asked for an estimate on what it will cost to fix the airbag problem and all the service guy has said is "expensive". So, I have no working airbags and I am not happy. I will try and fix it next spring when I buy a VAG-COM and have lots of time and patience. The car (98 A6Q) has 108K and I'd like to keep it for a few more years. Replacing both seats might be what it would take....Good luck.
BK
BTW: I think all of the computers in the car are hooked to the OBD connecter and any one of them can take down communications with the outside world. It's a CAN network, I think.

Is your car a 96 or 97 quatro with ECU P# 8D0 906 266 * ? If so, there may be some kind of anomaly with address 33, the generic OBD II portal. Over time I have veiwed these ECU's with our VAG-COM software, and the results are consistent: the OBD II test comes up negitive, and attempting to recover readiness codes says the function is un-supported. Oddly enough, the readiness codes are readily visible at VAG measuring block 029, field 1. Also the ECU sign on data clearly shows:

Address 01: Engine
Controller: 8D0 906 266 B
Component: 2,8l V6/2V MPI OBD2 D02

And furthermore I have an electronic document on one of my systems that implies that a VAG 1551 could in fact open address 33.

but indeed, any control module can "lock" the diagnostic bus, making all communications (including generic OBD-II) impossible.

-Uwe-