KOEO & KOER Codes (Hard Faults)

KOEO and KOER codes indicate faults are present at time of testing and should be serviced in order of appearance. A hard fault may cause CHECK ENGINE or Malfunction Indicator Light (MIL) to illuminate and remain illuminated until fault is repaired. If KOEO or KOER codes are retrieved during KOEO SELF-TEST or KOER SELF-TEST, see DIAGNOSTIC TROUBLE CODE IDENTIFICATION  table. Perform appropriate testing and repair procedures.