Key
Display messages
Possible causes/consequences and
M
M Solutions Â
Key does not Key does not
belong to vehicle belong to vehicle You have put the wrong key in the ignition lock.
X Use the correct key. Â
Replace key Replace key The key needs to be replaced.
X Consult a qualified specialist workshop. Â
Change key batter‐ Change key batter‐
ies ies The key battery is discharged.
X Replace the battery (Y page 88).Â
Key not detected Key not detected
(white display mes-
sage) The key is currently undetected.
X Change the location of the key in the vehicle.
If the key still cannot be detected: X Insert the key into the ignition lock and turn it to the desired
position. Â
Key not detected Key not detected
(red display message) The key is not in the vehicle.
A warning tone also sounds.
If the engine is switched off, you can no longer lock the vehicle
centrally or start the engine.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle to prevent it from rolling away (Y page 181).
X Locate the key.
X Press aon the steering wheel to confirm the display mes-
sage. Display
messages
301On-board computer and displays Z 
As soon as the vehicle is loaded:
X Prevent the vehicle from rolling away by
applying the electric parking brake.
X Shift the automatic transmission to posi-
tion P.
X Turn the key to position 0in the ignition
lock and remove it.
X Secure the vehicle. Notes for 4MATIC vehicles
! Vehicles with 4MATIC must not be towed
with the front or rear axle raised; otherwise,
the transmission may be damaged.
Vehicles with 4MATIC may either be towed
away with both axles on the ground or be loa- ded up and transported.
If the vehicle has transmission damage or
damage to the front or rear axle, have it trans-
ported on a transporter or trailer.
In the event of damage to the electrical
system: if the battery is defective, the auto-
matic transmission will be locked in position
P. To shift the automatic transmission to posi-
tion N, you must provide power to the vehi-
cle's electrical system in the same way as
when jump-starting (Y page 366).
Have the vehicle transported on a transporter
or trailer. Tow-starting (emergency engine
starting)
! Do not tow-start vehicles with automatic
transmission. You could otherwise damage the automatic transmission.
i Information on "Jump-starting"
(Y page 366). Electrical fuses
Important safety notes
G
WARNING
If you manipulate, bridge or replace a faulty
fuse with a fuse of a higher amperage, the
electric cables could be overloaded. This may result in a fire. There is a risk of an accident
and injury.
Always replace faulty fuses with specified new fuses of the correct amperage.
Blown fuses must be replaced with fuses of
the same rating, which you can recognise by
the colour and fuse rating. The fuse ratings
are listed in the fuse allocation chart.
The fuse allocation chart is on the fuse box in
the boot (Y page 374).
If the newly inserted fuse also blows, have the
cause traced and rectified at a qualified spe-
cialist workshop, e.g. a Mercedes-Benz Ser-
vice Centre.
! Only use fuses that have been approved
for Mercedes-Benz vehicles and which
have the correct fuse rating for the system
concerned. Otherwise, components or sys-
tems could be damaged.
The fuses in your vehicle disconnect faulty
circuits. If a fuse blows, all the components on the circuit and their functions will fail. Before replacing a fuse
X Safeguard the vehicle against rolling away
(Y page 181).
X Switch off all electrical consumers.
X Make sure that the ignition is switched off
(Y page 161).
or
X When using the key, turn the key to position
0 in the ignition lock and remove it
(Y page 161).
All indicator lamps in the instrument cluster
must be off. 372
Electrical fusesBreakdown assistance