Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Key ON Engine OFF (KOEO) Injector Electrical Self-Test
The KOEO injector electrical self-test is a functional test of the PCM carried out with the ignition ON and the engine OFF. This test determines if the injectors and circuits are correctly operating. If a concern is detected by the PCM, the corresponding DTCs are displayed at the end of the self-test.
- Turn off all accessories. If the vehicle is equipped with a PTO system or auxiliary idle control, it must be turned off to carry out self-tests.
- Carry out the necessary vehicle preparation and a visual inspection. Refer to QUICK TEST DESCRIPTION
- Refer to the scan tool manufacturers manual for instructions.
- Ignition ON, engine OFF.
- Carry out the KOEO injector electrical self-test.
- Ignition in OFF position.
- Record the DTCs and carry out the appropriate pinpoint test.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.