I have a 99 A6 Quattro Automatic that will not drive, I dont know the histrory of the car as I got from an auction knowing I will need to repair but it has me stumped, car runs great, no codes on engine or tranny modules using vagcom, I lifted the car and when I put it in drive the wheels spin, I can accelerate and see the tranny changing gears as speed increases but when I put it on the ground it will not move. Tranny fluid checked out OK, the only noise is from a rear right axle that seems to have a bad bearing.

Clarification on the wheels spinning, when in drive front wheels spin but rear wheels do not, checked drive shaft and it is turning, right rear axle turns but left axle doesnt turn.

 

Sounds like the clutches in the transmission are bad or slipping. I bet if you safely could hold each wheel still while off the ground, you could get them to stop spinning.

 

If the fluid level is okay, no forward drive generally means a rebuild. Get it to a tranny guy and have them do a diagnostic so you will know what happened. My guess is that you have low oil pressure and the big piston that pushes the clutch packs together is not pushing hard enough. Low oil pressure comes form various sources.

 

Ok, been a while but the car was fixed and drives good, the problem turned out to be the rear axle and not the tranny, right rear axle was making noise and was turning even when car is parked, I replaced the rear axle and that fixed it. Apparently 4WD will not allow the car to move if one axle is bad.

 

That's a problem with the Torsen style differential that Audi uses in the center diff - if one wheel can transmit 0 torque, that's it you are stuck. Good catch!

Bob