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.
Glow Plug Monitor
The glow plug monitor system is designed to detect glow plug or wiring concerns in the glow plug system. The glow plug system DTCs indicate which cylinder has a glow plug concern, glow plug wiring concern in the glow plug system and internal concerns.
The key ON, engine OFF (KOEO) test is carried out in order to test the glow plug control module (GPCM) control circuit for concerns. The glow plugs are not operated during this test.
The glow plug monitor self-test is a functional key ON, engine running (KOER) test of the PCM carried out on demand with the engine running and the A/C OFF. The PCM activates the GPCM which monitors the glow plugs. If necessary, use the accelerator pedal to increase the engine speed to increase voltage. A concern must be present at the time of testing for the test to detect a concern. The DTCs are sent to the PCM and output to the scan tool.
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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.