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.
Lens heating
The lens of the ACC sensor is made of plastic. The built-in lens heating ensures better availability of the Active Cruise Control option in winter weather conditions.
The lens heating is activated by the ACC sensor. The heating is controlled via a pulse-width modulated signal (PWM signal). The heating coil is integrated into the lens of the ACC sensor
The lens heating is only activated within a certain ambient temperature range (approx. +5°C to -5°C). Reason: Only at temperatures around zero is snow wet or moist. At temperatures well below this, snow will be dry. To prevent snow from thawing on the lens and creating an artificial coating, the heating is switched off below a certain ambient temperature. The current ambient temperature value is transmitted by the instrument cluster.
- Conditions for activation
- Engine ON
- ACC ON
- Ambient temperature between -5°C and +5°C
Safety cutout
- Temperature in ACC sensor over 50°C
- (measured by interior temperature sensor in ACC sensor control unit)
- Voltage greater than 16 volts
The safety cutout shuts down the lens heating. The Active Cruise Control option remains activated. (No fault memory entry)
- Monitoring
The lens heating is monitored for open and short circuits in the heating coil.
If the monitoring reports a fault, the Active Cruise Control option will be shut down. (Fault memory entry)
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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.