Hard Failures
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
Hard failures cause Malfunction Indicator Light (MIL) to illuminate and remain on until problem is repaired. If light illuminates and remains on (light may flash) during vehicle operation. Cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, PCM will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle runs but driveability will not be optimum.