check yellow engine light came on but runs good on 2005 Ford Focus

every time i start the car and i'm checked the gas cap

Asked by for the 2005 Ford Focus
1 answer
First thing you have to do once the check engine light comes on, is scan the car with a scanner. If you dont have a scanner you can take it to the nearest Autozone, they will do it for free, and see what code you are getting.