Your speed sensor is going out. it is located near where the engine is connected to the transmission but on the back side of the transmission near the bottom.
My speedometer works and the odometer does not because there is a plastic gear in the odometer that is broken.
Broken tooth in speedometer head. Replace speedometer head
The speed sensor is bad.
Speedometer gives a wrong reading for Yukon XL 2003?
Something's wrong with it and it needs fixing.... a car that works properly won't do that
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
Chances are you have a steel cable running from the speedometer to the transmission. Over time the cable gets dry. I had this happen on my 80 accord long ago. So I pulled out the cable and lubed it with grease and it worked fine after that. You can try spraying it with WD40 and see if that helps.
I think there is some kind of speed sensor attached to the transmission. Probably a bad conection, a true Chevy trait. VBdenny
Yes, tires that are larger or smaller in diameter than original factory size will cause a car's speedometer to be wrong.
whats wrong with it?
that depends what is wrong with it
Why doesnt your speedometer work on a 02 Mits Galant