KOEO & KOER DTCs

These DTCs 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 DTCs are retrieved during KOEO ON-DEMAND SELF-TEST or KOER ON-DEMAND SELF-TEST, use DIAGNOSTIC TROUBLE CODE REFERENCE CHART  to find appropriate system test to perform.