2015 MERCEDES-BENZ C-Class SEDAN change key battery

X
To unlock the vehicle: touch the inner
surface of the door handle.
X To lock the vehicle: touch sensor sur-
face 0043or0044.
Make sure that you do not touch the inner
surface of the door handle.
X Convenience closing feature: touch
recessed sensor surface 0044for an exten-
ded period.
Further information on the convenience
closing feature (Y page 99).
X To unlock the trunk lid: pull the handle on
the trunk lid.
Deactivating If you do not intend to use the vehicle for a
longer period of time, you can deactivate KEY- LESS-GO. The SmartKey will then use very lit-
tle power, thereby conserving battery power.
For the purposes of activation/deactivation,
the vehicle must not be nearby.
X To deactivate: press the0037button on
the SmartKey twice in rapid succession.
The battery check lamp of the SmartKey
lights up twice briefly and KEYLESS-GO is
deactivated.
X To activate: press any button on the
SmartKey or insert the SmartKey into the
ignition lock.
KEYLESS-GO and all of its associated fea-
tures are available again. KEYLESS-GO start function
Bear in mind that the engine can be started by any of the vehicle occupants if there is a
SmartKey in the vehicle. Changing the settings of the locking
system
You can change the settings of the locking
system. This means that only the driver's door and the fuel filler flap are unlocked when the
vehicle is unlocked. This is useful if you fre-
quently travel on your own.
X To change the setting: press and hold
down the 0036and0037 buttons simulta-
neously for approximately six seconds until
the battery check lamp flashes twice
(Y page 84).
If the setting of the locking system is changed
within the signal range of the vehicle, press-
ing the 0037or0036 button:
R locks or
R unlocks the vehicle
The SmartKey now functions as follows:
X To unlock the driver's door: press the
0036 button once.
X To unlock centrally: press the0036but-
ton twice.
X To lock centrally: press the0037button.
The KEYLESS-GO function is changed as fol-
lows:
X To unlock the driver's door: touch the
inner surface of the door handle on the
driver's door.
X To unlock centrally: touch the inner sur-
face of the door handle on the front-
passenger door or the rear door.
X To lock centrally: touch the outer sensor
surface on one of the door handles.
X To restore the factory settings: press
and hold down the 0036and0037 buttons
simultaneously for approximately six sec- 82
SmartKeyOpening and closing

Checking the battery
X
Press the 0037or0036 button.
The battery is working properly if battery
check lamp 0043lights up briefly.
The battery is discharged if battery check
lamp 0043does not light up briefly.
X Change the battery (Y page 84).
If the key battery is checked within the signal
reception range of the vehicle, pressing the
0037 or0036 button:
R locks or
R unlocks the vehicle
i You can obtain a battery from any quali-
fied specialist workshop.
Replacing the battery You require a CR 2025 3 V cell battery.
X Take the mechanical key out of the Smart-
Key (Y page 83). X
Press mechanical key 0044into the opening
in the SmartKey in the direction of the
arrow until battery compartment cover 0043opens. Do not hold battery compartment
cover
0043closed while doing so.
X Remove battery compartment cover 0043. X
Repeatedly tap the SmartKey against your
palm until battery 0087falls out.
X Insert the new battery with the positive ter-
minal facing upwards. Use a lint-free cloth
to do so.
X Make sure that the surface of the battery is
free of lint, grease and other contaminants.
X Insert the front tabs of battery compart-
ment cover 0043into the housing first and
then press to close it.
X Insert mechanical key 0044into the Smart-
Key.
X Check the function of all SmartKey buttons
on the vehicle. 84
SmartKeyOpening and closing

Problem
Possible causes/consequences and
0050
0050Solutions The engine cannot be
started using the
SmartKey. The on-board voltage is too low.
X Switch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work:
X Check the starter battery and charge it if necessary
(Y page 347).
or
X Jump-start the vehicle (Y page 349).
or
X Consult a qualified specialist workshop. The engine cannot be
started using the Start/
Stop button. The
SmartKey is in the vehi-
cle. The vehicle is locked.
X Unlock the vehicle and try to start the vehicle again. The SmartKey battery is discharged or nearly discharged.
X Check the SmartKey battery (Y page 84) and replace it if nec-
essary (Y page 84).
If this does not work:
X Start your vehicle with the SmartKey in the ignition lock. There is interference from a powerful source of radio waves.
X Start your vehicle with the SmartKey in the ignition lock. You have lost a Smart-
Key. X
Have the SmartKey deactivated at a qualified specialist work-
shop.
X Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. You have lost the
mechanical key. X
Report the loss immediately to the vehicle insurers.
X If necessary, have the locks changed as well. 86
SmartKeyOpening and closing

Display messages
Possible causes/consequences and
0050
0050Solutions 00AF
Replace Replace
Key
KeyBattery
Battery The SmartKey batteries are discharged.
X Change the batteries (Y page 84).00AF
Don't Forget Your Don't Forget Your
Key Key The SmartKey is not in the ignition lock. You have opened the
driver's door with the engine switched off.
This display message is displayed for a maximum of 60 seconds
and is simply a reminder.
X Take the SmartKey with you when you leave the vehicle. 00AF
Key Not Detected Key Not Detected
(white display mes-
sage) The SmartKey is currently undetected.
X Change the location of the SmartKey in the vehicle.
If the SmartKey still cannot be detected:
X Insert the SmartKey into the ignition lock and turn it to the
desired position. 00AF
Key Not Detected Key Not Detected
(red display message) The SmartKey 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 against rolling away (Y page 174).
X Locate the SmartKey.
X Press 0076on the steering wheel to confirm the display mes-
sage. Because there is interference from a strong source of radio waves,
the SmartKey is not detected whilst the engine is running.
A warning tone also sounds.
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 (Y page 174).
X Operate the vehicle with the SmartKey in the ignition lock. 00AF
Remove Remove
'Start'
'Start' But‐
But‐
ton and Insert Key
ton and Insert Key The SmartKey is continually undetected.
The SmartKey detection function has a temporary malfunction or
is faulty. A warning tone also sounds.
X Insert the SmartKey into the ignition lock and turn it to the
desired position.
X Visit a qualified specialist workshop. Display
messages
283On-board computer and displays Z