The only way to alter the mileage is to replace the instrument cluster if it's a digital readout. The mileage can be verified by connecting Chrysler's DRB2 or DRB3 computer and performing the "SRI" mileage check. It will ask if he the odometer reading is within 50 miles of the computer's reading.
When a speed sensor quits, both the instrument cluster and the engine computer stop accumulating mileage at the same time, so the vehicle could actually have a little more mileage than indicated, but not by very much.
Your car doesn't actually have a speed sensor like they did in previous years. It has an input speed sensor and an output speed sensor in the transmission. The transmission computer looks at them to detect clutch pack slippage in the various gears. When slippage is detected, or as in your case, when a sensor stops working properly, the computer defaults to "Limp-in" mode where it stays in second gear allowing you to drive the car slowly. You will also be able to select neutral, reverse, and park, but for forward, it will stay in second gear until you turn the ignition switch off and restart the engine. The clue it's only a sensor problem is the speedometer and odometer stop working. If the problem is internal slippage, which requires a rebuild, the speedometer usually stays working.
As for the temperature gauge, if it goes up and down a few times as the car warms up over about 5 to 10 miles, it needs to have a thermostat installed that has a very tiny bleed hole in it. Most people just ignore it. When the coolant hits 210 degrees, the electric fan will turn on and you will see the gauge come back down. The fan rarely runs while on the highway because there is already sufficient air flow to cool the radiator. It's common for the gauge to go up while sitting in traffic.
Saturday, December 12th, 2009 AT 2:04 AM