Hard Failures
WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, 1995 Dodge Caravan, and 1995 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
Hard failures will cause MIL to illuminate and remain on until malfunction is repaired. If MIL comes on and remains on (or light flashes) during vehicle operation, cause of malfunction must be determined using diagnostic tests.
If a sensor fails, PCM will use a substitute value in its calculations, allowing engine operation in limp-in mode. In this condition, vehicle will run but driveability will be poor.