Odometer Problem
 

I am driving a 2008 Marquis GS I bought in March 2014. This car has an analog speedometer and a digital odometer. The problem I am having, and has been ongoing for the last few months, is the Odometer is counting at least twice the normal rate. I have gone from 77,000 miles last November to 135,000 now and I average 50 mile a day. It's so bad that I have passed my warranty I took out when I bought the car. My mechanic says he has never seen this before. Someone has suggested that the sensor for the Odometer could be in the rear wheels and could have been damaged when I had the rear tires changed a few month ago.


Any ideas? If it is a sensor problem how do I fix it and reset the Odometer. Also is the true mileage perhaps in the computer somewhere?