Key On Engine Running (KOER) On-Demand Self-Test
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2005 Ford RV Cutaway, 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
The KOER on-demand self-test is an on-demand functional test of the PCM carried out with the engine running. Temperature is not a factor, but the air conditioning (A/C) must be turned off. A check is made on the injection control pressure (ICP), variable geometry turbocharger (VGT), and exhaust gas recirculation (EGR) systems. During this test, the engine RPM may vary. A fault must be present at the time of testing for the KOER on demand self-test to detect a fault. If a fault is detected, a DTC is output on the data link at the end of the test when requested by a diagnostic tool. Only a hard fault code DTC is displayed.