My car is a 2000 A6 with 2.8 engine.

I was driving with my cruise control set at about 70 mph, when suddenly the car accelerated to about 80, before cruise control kicked itself off. The check engine light came on, and cruise control did not work after that. I got my scanner to check engine code and it reported "vehicle speed sensor - incomprehensible signal" or something to that affect.

With about 192,000 miles on the clock I figured it was time to replace this part, so I went to the local parts store and got a replacement. I got the camera out to record the job and show the how to do this.

The new sensor is only $43 from Autozone
http://i1020.photobucket.com/albums/...t/100_0832.jpg

Access to the speed sensor will be through the drivers side wheel well. You can't reach it from below (frame is in the way) or above (everything is in the way).
http://i1020.photobucket.com/albums/...t/100_0831.jpg

When I looked inside, this is what i found. The speed sensor dangling against the axle shield!
http://i1020.photobucket.com/albums/...100_0835-1.jpg

Comparing the new sensor on the left to the old sensor on the right, you can see this broke apart inside the transmission.
http://i1020.photobucket.com/albums/...t/100_0836.jpg

Remove the axle shield to get better access. It's only 3 bolts, takes less than 5 minutes, and will finally allow you to see what you are http://i1020.photobucket.com/albums/...t/100_0839.jpg

With better access removing the remainder of the sensor was easy; the tab clicks underneath a tab on the transaxle. Here you can see that it came out in 2 pieces.
http://i1020.photobucket.com/albums/...t/100_0841.jpg

Snap the new sensor in place and connect the wire. Once this is done, put your axle shield back on and you're ready to wrap this job up!
http://i1020.photobucket.com/albums/...100_0842-1.jpg

Don't forget to clear codes now that you've replaced the sensor.
http://i1020.photobucket.com/albums/...t/100_0843.jpg

All that's left now is to put the wheel back on and go for a test drive. Car runs fine and cruise control works perfectly. The whole job took about 30 minutes.