Hard Failures

Hard failures cause CHECK ENGINE light to glow. Fault codes are stored in Electronic Control Module (ECM) memory. All codes except Codes 26 and 44 will cause CHECK ENGINE light to remain illuminated (with ignition on) until fault is corrected and ECM memory is cleared.

Codes 26 and 44 and the CHECK ENGINE light will remain on only until next ignition on/off cycle. Code will no longer be available to driver, but will still be stored in ECM memory.

If light comes on and remains on during vehicle operation, cause of malfunction must be determined using TROUBLE CODE IDENTIFICATION  table. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional but poor driveability may occur.