Hi, I Have a 1998.5 Audi A4Q 2.8L (manual trans) and i recently had a flat tire, so i replaced it with the factory spare.. a few days later when i got my car back from les schwab i noticed my Speedometer is no longer working. it has been about 3 months now, and im relying on my Speed from a iPhone app i have. i was wondering if anybody knows what's causing my speedometer to not work??? could it be the speed control sensor? the ABS Speed Sensor??? I have no clue and would greatly appreciate the help!!! thank you soo much !

P.S. all other guages work, tach, temp, middle screen, oil temp, ect...

Thank You Again.