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 go on and remain on until fault is repaired. If KOEO or KOER codes are retrieved during KOEO SELF-TEST  or KOER SELF-TEST, use the DIAGNOSTIC TROUBLE CODE (DTC) REFERENCE CHART  to find correct testing and repair procedures.