Hi guys. Just bought myself a 2006 Audi A6 3.2 quattro yesterday. Took it for a test drive, everything was perfect. After about 5 or 6 hours of uneventful driving, we went to overtake up a hill and the car shifted down. Once we overtook the other car, the audi stayed in 4th or 5th gear at 3,500 rpm and wouldn't shift. The gear selection display on the dash highlighted red and the engine light came on. I stopped, put it in park, turned it off and the red highlight went away, but the engine light is still on. Now Im Getting "PRNDS" and then a "123456" depending on what gear im in, so it appears as "PRNDS 4" if im in 4th gear. Now if im going up a hill and it needs to be in 2nd to make it up, it stays in 2nd once im at the top and need to shift up. However, the tiptronic works perfectly, so thats how I drove it the rest of the way home. I went to autozone and the code read "transmission speed sensor". I would like any input if anyone's ever had this before and how much you think it will be to replace. There are a few independent european car mechanics around here, so there is a very slim chance of me taking it to the dealership. Thanks in advance