KOEO & KOER Codes
WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
KOEO and KOER DTCs indicate faults are present at time of testing. A hard fault may cause Malfunction Indicator Light (MIL) to illuminate and remain illuminated until fault is repaired. The MIL is located on instrument cluster and may be labeled SERVICE ENGINE SOON or CHECK ENGINE. If KOEO or KOER DTCs are retrieved during KOEO ON-DEMAND SELF-TEST or KOER ON-DEMAND SELF-TEST, see DIAGNOSTIC TROUBLE CODE DEFINITIONS to find appropriate system test to perform.