Anything that can change the emissions of the vehicle. Engine sensors, EGR, gas cap, transmission, etc.
Lots of possibilities, Check ignition modul first.
Yes, that is one of hundreds of possibilities.
Yes, that is one of hundreds of possibilities
Possible, but not likely. The check engine light is mainly for emission failures not fluid levels. Have it checked for codes to know the cause.
A clogged or defective fuel filter will very likely cause a check engine light. If it is suspected, it should be replaced.
If the check engine light has not come on, it is most likely a vaccume leak.
Not likely. A bad O2 sensor would illuminate the check engine light and the engine performance would suffer.
Not likely. Have the system checked for codes to know possible causes.
Most likely cause is a burnt out inlet valve. You need to do a compression check.
Yes, that is one of hundreds of possibilities for the check engine light.
Yes, an unplugged sensor can cause a check engine light.
Lack of proper airflow to the engine is the most likely cause. Check to see if your intakes are clear of any debris and whether or not any coolant lines in the engine are loose/leaking. Some other possibilities, stuck thermostat, plugged radiator, bad fan clutch, blown head gasket, cracked head, missing fan shroud.