Key On, Engine Off (KOEO) Self-Test
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KOEO self-test is a functional test of PCM performed with ignition switch turned to ON position, engine off. This test checks if PCM input and output devices 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.