System self-test
The 42 indicator lamp illuminates when you:
• turn the SmartKey to position 1 or 2 in the
ignition lock
• on vehicles with KEYLESS-GO, press the
Start/Stop button once or twice
The 
indicator lamp goes out
again after approximately six seconds.
If the indicator lamp does not
illuminate or is lit continuously, the system is
malfunctioning. Have the BabySmart™
system checked at an authorized Mercedes-
Benz Center before transporting a child on
the front-passenger seat.
For further information, see "Problems with air bag deactivation system".
WARNING 
Do not place powered-on laptops, mobile
phones, electronic tags such as those used in
skipasses or similar electronic devices on the
front passenger seat. Signals from such
devices may interfere with the BabySmart™
air bag deactivation system. Such signal
interference may cause the
indicator lamp not to come on during self-test.
The + SRS indicator lamp and/or the
indicator lamp could be
continuously lit, indicating that the system is
not functioning. The front-passenger front air
bag could deploy inadvertently or fail to
deploy in an accident.
See also:
SRS warning lamp
SRS functions are checked regularly when
you switch on the ignition and when the
engine is running. Therefore, malfunctions
can be detected in good time.
The SRS warning lamp in the
instrume ...
Vehicle identification plate
Even if you have calculated the total load carefully, you should still make sure
that the gross vehicle weight rating and the gross axle weight rating are not exceeded.
Details can be found on the ...
General notes
DISTRONIC PLUS regulates the speed and
automatically helps you maintain the
distance to the vehicle detected in front. It
brakes automatically in order to avoid
exceeding the set speed.
On lo ...