Check engine light

The engine computer detected a problem and set a diagnostic fault code. Since this problem could adversely affect emissions, it also turned on the check engine light. The place to start is by having the fault codes read and recorded. The people at many auto parts stores will do that for you for free.

Be aware fault codes never say to replace parts or that one is bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a part is referenced in a fault code, it is actually the cause of that code about half of the time. First we have to rule out wiring and connector terminal problems, and things like that, before spending money on a part.