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.
Rear Demist
There are heating loops in the glass for demisting and to prevent ice from forming. The loops heat up when they are supplied with power. The power supply is via a relay on the central electronic module (CEM).
Rear demist is controlled via a switch located on the climate control module (CCM) it can also be activated by selecting auto defrost rear, on the climate settings in the menu for the Infotainment control module (ICM).
Automatic rear demist starts when the engine starts and the outdoor temperature is below +9 °C.
In order to switch off the function before it is switched off automatically press in the switch again. Automatic switching off of the rear demist is dependent on the outdoor temperature according to
- above +7°C: activated for 12 minutes and then switched off.
- +7°C to -15°C: activated constantly for 20 minutes - it then switches to pulsing, 5 minutes activated and 1-10 minutes deactivated. The time it is deactivated is linearly dependent on the temperature.
- below -15°C: activated for 20 minutes, then pulsing 5 minutes activated and 1 minute deactivated.
There are diagnostics for the relay and switch.
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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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