Why did engine light come on?
The engine light came on but the car is running good and engine oil is topped up.
Carol O'Brien, there can be plenty of reasons for that. Something as simple as a bad gas cap to pretty much any sensor, could have caused that. I suggest to get it scanned for any OBD codes. Not sure where you are located, but Autozone and other parts places offer free scans. Let us know what you find.
i had a bad air flow sensor, but my engine still comes on after a new air flow sensor was put in, trying to find answer what could cause it to idle real low and engine light come on