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.
64 99... Fault 03 Glow plug
Test Precondition:
Overheating protection not active. Voltage supply at independent parking heater O.K.
Instruction:
Switch on independent heater via MID or on-board monitor.
Measure voltage of glow plug at peripherals box (pin allocation: refer to DIS circuit diagram).
Specified value: Voltage switches between 0V and 12V
| Question | Measure | |
|---|---|---|
| Is supply voltage O.K.? | No | Replace independent parking heater control unit, refer to 64 12 520 REMOVING AND INSTALLING/REPLACING CONTROL UNIT WITH HEAT EXCHANGER (THERMO TOP S) . |
| Yes | Switch off park heating, remove connector from glow plug and measure resistance. | |
| Specified value: 3 Ω +/- 1 Ω Is measured value within valid range? |
No | Replace glow plug, refer to 64 12 505 REMOVING AND INSTALLING/REPLACING GLOW ELEMENT (THERMO TOP S) . |
| Yes | Glow plug is O.K. | |
NO RELATED
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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.