Hard Failures

Hard failures (emission-related faults) cause MIL to illuminate and remain on until system or component passes the same test for 3 consecutive drive cycles without a fault. If vehicle is experiencing a misfire malfunction which may cause damage to Three-Way Catalytic Converter (TWC), MIL will flash once per second. This will continue until vehicle is outside of speed and load conditions which could cause possible catalyst damage, and MIL will stop flashing and remain on steady. If light comes on and remains on (light may flash) during vehicle operation, determine cause of malfunction using diagnostic (code) charts. See SELF-DIAGNOSTICS - INTRODUCTION article. If a sensor fails, Powertrain Control Module (PCM) will use a substitute value in its calculations to continue engine operation. In this condition (limp-in mode), the vehicle will run, but driveability will not be optimum.