I have an audi tt quattro 2000 moodel and I have a problem with the quattro system.

The rear differential does not spin. The axle that unites the front and rear differential spins but the rear wheels have no movement. There is no noise from the rear differential that might indicate that something is broken within the differential. We have also emptied the oil of the differential to check whether there were any pieces but the oil was clean.

We have also used the diagnostic and it showed error with the speed sensor (however i dont know whether the 2 error are related or not).

PLEASE HELP!!! THANKS