KOEO & KOER Codes (Hard Faults)
WARNING: This page is about a different car, the 1995 Ford Pickup, 1995 Ford Econoline, 1995 Ford Club Wagon, and 1995 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
These codes indicate faults are present at time of testing. A hard fault may cause CHECK ENGINE light 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 DIAGNOSTIC TROUBLE CODE REFERENCE CHART to find correct testing and repair procedures.