Front collision detection.
Out in the slushy snow today and after about 2 miles got a warning beep and yellow display indicating the collision detector wasn't working. Sussed immediately that it was likely to be covered in snow. Once we'd parked up I decided to switch the system off because the stupid light was annoying me. What happens if you switch the system off? The stupid light is on all the time! I don't need a warning light to tell me that I have switched a system off - I know because I did it!