The sensor is required for the original retrofitting of: Rain/light sensor Coming home - Leaving home Suitable for: Audi A3 8V Audi A5 8F Cabrio The rain sensor automatically adjusts the wiper frequency depending on the intensity of the rain The light sensor measures the incident light and automatically decides in which lighting mode the headlights are switched on The Coming home - Leaving home function switches on the dipped beam headlights, exterior mirror lights, tail lights and license plate lights when the car is opened with the radio remote control (leaving home) and delays the switching off of these lights when returning home Scope of delivery: 1x rain/light/humidity sensor Note: If no humidity sensor is installed, the front window must also be replaced and the cable set 39980 must be used