OK 97 A4 quattro, all shift lights lit up on dash, , no reverse, all other gears OK. Previous owner had the MFS changed abt. a year ago. So after searching this site we decided to check and clean the MFS plug, it was all green with corrosion, so I cleaned with contact cleaner, put some di-electric grease, sealed plug where wire enters with silicone as this is where the moisture penetrated. Ok , so now we get reverse sometimes, sometimes no, some threads say you have to clear the code for it to work. So we put the code reader on and get 0023-MFS (F125) 27-10 Implausible Signal-Intermittent, clear the code all shift lights go out, put it in reverse, nothing, in drive and the lights go back on. So do I assume I need a switch or are we doing something wrong after erasing codes. If I need a switch , is a used one out of the question, I am within 10 miles and 20 miles of 2 Audi bone yards.
That was the only code coming up when scanning tranny, engine codes show 17091-P0707-35-00 to decode all DTC's, 17956, 18032-MIL Request, signal active , Check TCM for errors too,P1624-35-10 Inter. Do any of these have to do with the tranny?

 

Ok so in case this might help someone else my findings were, which are pretty much obvious, if you clean the plug, clear the code, but it comes right back, then you need a switch, got mine from VW Parts (they do Audi's too) in Fleischmanns NY $125 used. Also remember to tie wrap the wire at the plug and put a nice dab of silicone around it as, this is where oil, water etc. enters, creates a short and burns out the switch.

 

I am having similar issues, and am trying to troubleshoot. Can you remember what your car did when it did not have "reverse"??? When you put the shifter in reverse, did it feel like it shifted into reverse, but it just wouldnt move, or did it just switch into gear without any kind of movement from the trans (like when you put it in neutral)???

Mine feels like it is going into reverse("clunks or jumps a little" like any automatic) but when you press the gas, nothing. Also, my RPMs will not go above 2K....its like its in gear, but you have the parking brake on.

Thanks for any help.

 

So replacing the multifunction switch fixed your car?

 

My car is still running fine, sounds like your car may be a different issue,it sounds almost like yours is slipping, because mine really didn't do much, IIRC it might have clicked a little, but felt like it was totally in neutral, then even when we put the switch in, still like neutral, until we cleared the code. You should pull the plug, the terminals will be all green with corrosion, just clean good with electrical cleaner spray, put some dielectric grease, put back in, clear you code, if it works, it was the plug, if it goes out again it's the switch, it's worth a shot, for sure, theses switches are known to go out.