Reasons your engine check light on
1.Spark Plugs (time for a tune-up)
2.Thermostat
3.Oxygen Sensors ( O2 Sensors)
4.Gas cap lose/missing
5.Catalytic converter
6.Mass airflow sensors
7.Low coolant in the radiator
8.Electrical problem such as fan not working
9.Spark plug wires
10. Alternator problems