I have a 2001 Audi a6 2.8 quattro and I am experiencing some problems with the speedometer. When you are driving the speedometer will randomly start reading false speeds and bouncing all over. If you have the cruise control on while driving on the interstate and the car starts malfunctioning going faster...slower...faster all over the place. Just need to know what could be causing this. I am thinking it is the vehicle speed sensor but am not sure...anyone know where this is located and how much it is to replace.
thanks
Harry

 

Had similiar problem with my 1998 a6 2.8 quattro with automatic transmission. A faulty speed sensor was the cause as you suggested. ECS tuning sells them for about $58. It is a relatively easy repair. The sensor is located in the front differential next to the transmission. It is accessed from under the car. Ramps work well. Remove connector for the sensor, press down on clamp for sensor, turn and remove it. Installation is the reverse. Mine was stuck and I had to break it to get it out.