Suddenly a yellow light illuminates on your dash telling you to check or service your engine. The yellow warning indicator may be labeled "check engine," "service engine soon" or "check powertrain" or the light may be nothing more than a picture of an engine. When you see that light, your car’s computer has recognized a failure in one of your systems.  The light can mean many different things, from a loose gas cap to a seriously misfiring engine.  Your Owner’s Manual will help you understand the different scenarios that may cause the check engine light to illuminate.