KOEO & KOER DTCs
WARNING: This page is about a different car, the 2000 Mercury Mystique, 2000 Ford Pickup, 2000 Ford F550 Super Duty, 2000 Ford F450 Super Duty, and 2000 Ford Contour. However, it is still accessible from the selected car via links, so may be relevant.
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.