Hard Failures

Hard failures cause MIL to illuminate and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined by retrieving Diagnostic Trouble Codes (DTCs). See RETRIEVING DIAGNOSTIC TROUBLE CODES  . If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle will run, but driveability will not be optimum.