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) Self-Test
1) This is a test of electronic engine control system, conducted with power (voltage) applied and engine not running. Enter self-test. Record all codes displayed.
2) Erase codes. Repeat self-test. Diagnose only codes occurring during repeat self-test. See TROUBLE CODE IDENTIFICATION table. If no codes are present, proceed to KEY ON, ENGINE RUNNING (KOER) SELF-TEST.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.