Drove through a big puddle and now the reverse will not function on the 1997 Audi A4 1.8 Quattro. What can it be? It works in park and drive. Help! Took it to a foreign car repair and they said they didn't know what was wrong - $18 please.

there is a switch on the top of the transmission that over time looses is water proofing and is prone to getting wet (at least on the A6 from 97) if this is the same problem the Audi dealership should be able to replace and repair the problem for less than $100. I had the same problem a year or so ago on my A6 i think it cost me $75 to have it fixed. But there is also the chance that the puddle had nothing to do with it and you need tranny fluid the no reverse s the first symptom of a leaking tranny that needs fluid. But most likely it is the switch that got wet and is now bad.

Take the car to a genuine Audi repair shop where they can scan the OBD computer with proper equipment. Chances are, since you drove through a puddle, that an electrical lead was damaged or moved away from it's proper terminal. This should be relatively easy to find and repair. Be sure to check that your trans fluid is up to it's proper level, and only use genuine Audi trans fluid (which is gold in color because it is mineral based). This shouldn't be an expensive repair, mostly tough to find a knowledgeable person capable enough to deal with it. Good Luck!!!