Key On, Engine Off (KOEO) Self-Test
WARNING: This page is about a different car, the 2002 Ford Escape, 2001 Mazda Tribute, and 2001 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
KOEO self-test is a functional test of PCM performed with ignition switch turned to ON position, engine off. This test checks if PCM inputs and outputs are functioning electronically without any faults. KOEO self-test displays on-demand hard DTCs. These DTCs usually are electrical open and/or short circuits and must be serviced first, before any other type of DTCs. A fault must be present at time of testing for KOEO self-test to detect a fault.