See also:

Collision warning
The concep The system issues a two-phase warning of a danger of collision at speeds above approx. 10 mph/15 km/h. The time of these warnings may vary depending on the current driving situation. ...

Deactivating HDC
Press the button again and the LED goes out. HDC is automatically deactivated above approx. 37 mph/60 km/h. ...

Malfunction
A message is displayed in the instrument cluster. HDC is not available, e.g., due to elevated brake temperatures. ...