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.
Self-Test Procedures
Perform Key On Engine Off (KOEO) and Key On Engine Running (KOER) self-test procedures with one of the following: SUPER STAR II tester, analog volt-ohmmeter (VOM), or CHECK ENGINE light.
KOEO codes include hard and intermittent failures. To determine failure(s) type (hard or intermittent), record and clear codes stored in ECA memory. Operate vehicle and repeat KOEO self-test. Codes that immediately reappear are hard failures. Codes that do not reappear are intermittent failures.
Repair hard failures, in the order of code appearance, before performing KOER self-test. Use CODE REFERENCE CHART to determine the correct CIRCUIT TEST. Codes may be cleared from the ECA memory after they have been recorded and/or faults repaired. See CLEARING CODES. If no trouble codes are found during KOEO self-test, proceed to KOER self-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.