My 2002 lancer spedometer doesn't show the correct speed . Do I need to replace the 02 sensor.

 

No. The O2 sensor detects how much unburned oxygen is present in the exhaust gases to determine if the mixture was too rich or too lean and adjust accordingly. It doesn't have anything to do with your speedometer. There's a few factor that can affect your speedometer from displaying the right speed of the vehicle. Changing your wheels to a different size (i.e. going from 16 to 18) or your stepper motor on your gauge is about to go out are the few. We need to know if you change anything lately.

 

Well when I bought the car in November the spedometer didnt work . But there are aftermarket rims on the car . If I were to get a new spedometer would it fix the prob

 

So there are still aftermarket rims on it? then no a new spedo won't work... you need stock wheels sizes or else you are going to have to deal with the speedo difference to actual speed.

 

The rims look like they are stock size. They are like 16 or 15 inch rims. If your saying that that I have to put stock wheels on In order for the spedometer to work how come no one else has that problem. Plus I don't have the stock wheels lol