Replace Rain-Light Sensor
WARNING: This page is about a different car, the 2005 BMW 645Ci and 2004 BMW 645Ci. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
When replacing the rain-light sensor, use only the rain-light sensor for the head-up display!
The head-up display requires a special rain-light sensor so that the display brightness can be adjusted optimally.