Mercedes-Benz ML320 Cdi Operator's Manual page 435

Practical hints
What to do if ...
Display message
DISTRONIC
currently unavailable
See Operator's Manual
434
Possible cause/consequence
Distronic* is deactivated because
the Distronic* cover in the
radiator grille is dirty
the functionality is impaired by
heavy precipitation or fog
Possible solution
Clean the Distronic* cover in the radiator
grille ( page 408).
Restart the vehicle.
Distronic* becomes operational again without
the engine being restarted when
dirt on the radiator grille has fallen off while
driving (e.g. slush or snow)
the system recognizes full sensor
availability due to lessening rain or because
the road is drying, for example
the message in the multifunction display
disappears
You can then operate Distronic* as usual again.