Key ON Engine Running (KOER) Self-Test

The KOER self-test is a functional test of the PCM carried out with the engine running. The engine must be at operating temperature for the KOER self-test to operate. A check is made on the fuel rail pressure (FRP) sensor, turbocharger, and exhaust gas recirculation (EGR) systems. During this test, the engine RPM may vary. The brake pedal position (BPP) test is a part of the KOER self-test and must be carried out during this operation. A concern must be present at the time of testing for the KOER self-test to detect a concern. If a concern is detected, a DTC is output on the data link at the end of the test when requested by the scan tool.