Hard Failures

A hard failure will cause MIL to come on and remain on until the malfunction is repaired. If MIL comes on and remains on (or flashes) during vehicle operation, cause of malfunction must be determined using diagnostic code charts.

If a sensor fails, ECM will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, vehicle is functional but driveability may be affected.