KOEO & KOER Codes (Hard Faults)
WARNING: This page is about a different car, the 1995 Mazda B4000, 1995 Mazda B3000, and 1995 Mazda B2300. 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, see DIAGNOSTIC TROUBLE CODE DEFINITION CHARTS to find correct testing and repair procedures. Record and service codes in order received.