See also:

Switching off automatically
System switches off: above approx. 9 mph/ 15 km/h. Switch on the system again if necessary. ...

Warning stages
Prewarning This warning is issued, for example, when there is the impending danger of a collision or the distance to the vehicle ahead is too small. Acute warning with braking function Warning ...

Automatic deactivation during forward travel
The system switches off when a certain driving distance or speed is exceeded. Switch the system back on if necessary. ...