Do you mean the "Service Engine Soon" light or the "Check Engine" light? Those mean the Engine Computer has detected a problem and has set a diagnostic fault code in memory. Do not remove a battery cables or that valuable information will be lost.
Many auto parts stores will read those codes for you for free. They will get you into the circuit or system with the problem, not necessarily to the defective part.
Apr 13, 2011 at 7:40 PM