An illuminated engine warning light means your vehicle has detected a potential fault.The computer has detected one or more diagnostic trouble codes and turned on the warning lamp to alert you to the problem.
There is no way to determine what the problem is without connecting a diagnostics computer to the vehicle's diagnostic connector to read the fault code(s). Once this has been done, further diagnosis and testing may be required to isolate the problem.
Depending on the nature of the fault, your engine may not run as good as it normally does, or it may use more fuel than usual. But usually the problem requires attention as soon as it is possible. You can continue to drive your car until it can be diagnosed.
Common reasons for the check engine light to come on include the failure of an engine sensor such as the oxygen sensor, throttle position sensor or manifold absolute pressure sensor, or a problem in an emissions control system or such as the catalytic converter.