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.
Using MIL
Malfunction Indicator Light (MIL) can be used for DTC retrieval and front Heated Oxygen Sensor (HO2S) monitoring. See Fig 1 . When ignition is turned on with engine off, MIL should illuminate. This is a bulb check. If MIL does not illuminate, repair MIL circuit. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT or, see DTC P0650: MIL (CIRCUIT) under DIAGNOSTIC TESTS. When engine is started, MIL should go off. If MIL remains on, ECM has detected a malfunction. If MIL is flashing when engine is running, ECM may be in diagnostic test mode II.
Use the Manual With the Right Hardware
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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.
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