I have a 94z28 A4 w/ just bolt-ons. One morning i noticed the car would not go into overdrive. After further investigation it ended up having only 2nd and 3rd gear going forward, with the exception of starting up (it started in 1st and would not downshift back afterward). Pulled the transmission and had it rebuilt and reinstalled and it still does the same thing. I took it back to the transmission shop. They looked at it, replaced the shifting solenoids again and that still did not fix the problem. The conclusion they came to was the the PCM was the cause.

After searching the forums I diddn't see any thing about PCMs failing on their own. Is it possible that's the problem or does the transmission place not have a clue?

 

I've heard that it can happen. Weirder things have happened. You can always go by the GM dealership and have them flash it again.