Ok so a few days ago, the speedometer was not hooked up to the back of the panel so I hooked it on and now it works like it should. This morning, i get in the car to go to work and everything but the MPH reader works. I got home from work and checked the cable and the cable is fine and its hooked up. After a few minutes of driving it like that, the check engine light come on, but it turns off once you turn the car off, then comes back on again after a few more minutes of driving. Anybody know what it could possible be?? Any help is appreciated.