Service Codes

These 3 types of service codes can be retrieved during self-test procedure: Key On Engine Off (KOEO), Key On Engine Running (KOER) and Continuous Memory. See Figure . See QUICK TEST for self-test procedures. Codes may be cleared from Electronic Control Assembly (ECA) memory by technician after they have been recorded or repaired. See CLEARING CODES .

KOEO & KOER Codes (Hard Faults) - These codes indicate faults are present at time of testing. A hard fault may cause CHECK ENGINE light to glow and remain on until fault is repaired. If KOEO or KOER codes are retrieved during KOEO SELF-TEST or KOER SELF-TEST, use KOEO SELF-TEST CODE REFERENCE table or KOER SELF-TEST CODE REFERENCE table to select correct CIRCUIT TEST (TEST) for testing and repair.

Continuous Memory Codes (Soft Faults) - Continuous Memory Codes are retrieved during KOEO SELF-TEST. These codes may cause CHECK ENGINE light to flicker or glow. Light will go out after fault goes away. These faults indicate a defect that may or may not be present at time of testing; however, corresponding trouble code will be retained in ECA memory.

If fault does not reoccur within 40 warm-up cycles, code will be erased from ECA memory. Continuous memory failures may be caused by sensor, connector or wiring problems. See INTERMITTENTS in TESTS W/O CODES article.

CAUTION: Record Continuous Memory Codes when received during KOEO SELF-TEST. These codes may be used to identify intermittent problems that exist after all KOEO and KOER codes have been repaired and a Code 11 or 111 (pass code) has been obtained. Some Continuous Memory Codes faults may not be valid after KOEO and KOER codes are repaired. Failure to follow this procedure may result in unnecessary testing and replacement of non-faulty components.