SMART forfour Owner's Manual page 180

Display messages (on-board computer with colour display)
178
Display messages
^
Distance warning
inoperative
Possible causes/consequences and M Solutions
The distance warning function is temporarily inoperative.
Possible causes:
the smart logo in the radiator trim is dirty
R
the function is impaired due to heavy rain or snow
R
the radar sensor system is temporarily inoperative, e.g. due
R
to electromagnetic radiation emitted by nearby TV or radio
stations or other sources of electromagnetic radiation
the system is outside the operating temperature range
R
the on-board voltage is too low
R
Once the causes listed above no longer apply, the display mes-
sage goes out.
The distance warning function is operational again.
If the display message does not disappear:
X
Pull over and stop the vehicle safely as soon as possible,
paying attention to road and traffic conditions.
X
Secure the vehicle against rolling away (
X
Clean the smart logo in the radiator trim (
X
Restart the engine.
Y
page 138).
Y
page 223).