When the "check engine" light comes on, it is important for the on-board diagnostics system in the car to be checked out in a timely manner. This can be done with an OBD scanner by the car owner or a qualified mechanic.
There are a few reasons for the "check engine" light coming on in a car. A steady "check engine" light may indicate smaller problems such as a loose gas cap or worn spark plugs. A blinking light may indicate a more serious problem, such as a faulty O2 sensor or fuel that has not been burned being dumped into the wrong areas.