KOEO & KOER Codes (Hard Faults)

These codes indicate faults are present at time of testing. A hard fault may cause CHECK ENGINE or MALFUNCTION INDICATOR LIGHT (MIL) 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 SERVICE CODE REFERENCE CHARTS  to find correct testing and repair procedures.