Sorry for a duplicate post but i didnt even get a response in the tech forum.


So the other day I was driving and the car dropped down to 2nd gear. I could not use the paddle shifters to upshift. But after a second or two the transmission up shifted finally. Everything was good for about 30 minutes or so, and then it did it again. This time I noticed that the speedometer would drop to zero. But there were no codes

So the next day i took the car out to test it one more time and pay attn to all the symptoms. So sure enough the car did it again and the speedometer dropped to zero like previously. However this time I got a service traction control light. And this time the car actually threw a code and stuck me in limp mode.

So not too long after that, I got the car over to my buddies shop and we scanned it. We cannot get any communication from the TCM and could only get a u1000 code. Due to the previous symptoms I kind of assumed it was the VSS. So I bought the one listed for my car, and I crawled under the car and looked at the rear diff to pull it out and I noticed that theres not one there like on my 06'. This is on a 2011 GS. So is the vss in the tranny pan on the A6? Anyone have a diagram of where?

But that brings up the question, could a bad oss even cause the U1000 no tcm communication error? Or do i need to chase down something else?

 

The only time I had anything like this happen to me was with a Torqueflight and it was incredibly low on fluid (dealership had installed new radiator under warranty and left transmission cooling lines loose.)

 

The sensor is located in the top, rear, right side of the diff. Here is a drawing of a M6, the A4 should be very close.

however, the U Code refers more to loss of communication, possibly a battery or ground issue................. I would expect a bad VSS to possibly set a P Code