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.
Chart A-2, Won't Flash Code 12
The CHECK ENGINE light should always stay on when ignition switch is in ON position and engine is not running. When diagnostic terminal is grounded the ECM will flash a Code 12, followed by any additional trouble codes. A steady CHECK ENGINE light might be a short to ground or an open diagnostic terminal.
- This checks for a grounded light circuit.
- This checks if problem is an open circuit in the diagnostic terminal or a faulty ECM.
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.