Hard Failures

Hard failures cause MIL to come on and remain on until failure is repaired. If MIL comes on and remains on (MIL may flash) during vehicle operation, cause of failure may be determined by using DTCs. See DIAGNOSTIC TROUBLE CODES (DTCS)  . If a sensor fails, ECM will use a substitute value in its calculations to continue engine operation. In this condition (limp-in mode), vehicle is functional, but loss of good driveability may result.