|CHECK ENGINE LIGHT
The Check Engine light is a warning system that lets the driver know that something isn't functioning correctly. The ECU is constantly receiving data from its sensors and if any one of them malfunction or get a reading that is out of the ordinary, the ECU immediately illuminates the CEL and stores the relative code in its memory.
Any number of problems could cause the ECU to throw a code. Certain non-detrimental problems may cause a 'SOFT CODE' meaning the car still drives 100% normal however, the CEL is illuminated notifying that there is still a problem or some kind such a misfire, too rich or lean mixture, etc.
Other more potentially harmful problems that the ECU detect will throw the car into what is called 'LIMP MODE' where the ECU instantly retards the timing and dumps an overly ambundant amount of fuel into the motor, robbing it of power so that one can still 'limp' the car home under power but limit the driver from causing any more damage. Problems such as MAP sensor malfunction, low oil or excess knock will send the ECU into Limp Mode.
In either case, it would be helpful to know what the problem was that the ECU has detected since a CEL light in the dash doesn't tell you much. If you could determine the code that the ECU threw, than one could easily pin point the problem and get it fixed immediately.
Click here to find out how to retrieve the CEL code.