Key On Engine Off (KOEO) On-Demand Self-Test
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.
The KOEO on-demand self-test is a functional test of the powertrain control module (PCM) carried out on-demand with the key on and the engine off. This test will carry out checks on certain sensor and actuator 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 as requested by a diagnostic tool.