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.
Hard Failures
Hard failures cause CHECK ENGINE light to glow. Fault codes are stored in Electronic Control Module (ECM) memory. All codes except Codes 26 and 44 will cause CHECK ENGINE light to remain illuminated (with ignition on) until fault is corrected and ECM memory is cleared.
Codes 26 and 44 and the CHECK ENGINE light will remain on only until next ignition on/off cycle. Code will no longer be available to driver, but will still be stored in ECM memory.
If light comes on and remains on during vehicle operation, cause of malfunction must be determined using TROUBLE CODE IDENTIFICATION table. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional but poor driveability may occur.
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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.