Ain't a sensor problem. (You lucky son of a gun). All you have to do is drive faster than half of the maximum speedometer reading. If it reads 120 mph max, drive 65 mph. The speedometer is no longer the common sense simple spring-loaded pointer driven by a cable. It is positioned by the instrument cluster, which is a computer module, by pulsing four coils of wire, (electromagnets). Something caused it to stay or go to more than half way. The next time the ignition switch was turned on, it looked for the shortest way back to "0" which was the wrong way. Once you drive faster than half the maximum speed, it will again search for the shortest way to the right speed, then it will just follow it back down like normal when you slow down. There are two other ways to reset it. One is to remove the Plexiglas cover and push the pointer back, or the dealer can connect their scanner and run all of the gauges through a test procedure that runs them all the way up in steps, then back down.
Sunday, March 20th, 2011 AT 9:15 PM