Key On Engine Off (KOEO) On-Demand Self-Test

The KOEO on-demand self-test is a functional test of the PCM or the TCM, and is carried out on demand with the ignition key in the ON position and the engine OFF. This test carries out checks on certain input and output circuits. A fault must be present at the time of testing for the KOEO self-test to detect the fault. When a fault is detected, a DTC is output on the data link at the end of the test when requested by a diagnostic tool. The KOEO on-demand self-test can be executed with the gear selector in PARK only.