change key battery MERCEDES-BENZ C-Class SEDAN 2012 W204 Owner's Manual

This device complies with RSS-210 of
Industry Canada. Operation is subject to
the following two conditions:
1. This device may not cause harmful
interference, and
2. this device must accept any interference
received, including interference that may
cause undesired operation.
Any unauthorized modification to this
device could void the user’s authority to
operate the equipment.
The Product label with FCC ID and IC
certification number can be found in the
battery case of the SmartKey.
Important notes on the use of KEYLESS-
GO
R The KEYLESS-GO key can be used like a
conventional key.
R You can combine KEYLESS-GO functions
with those of a conventional key, e.g.
unlock with KEYLESS-GO and lock with the
& button.
R Always carry your KEYLESS-GO key on your
person.
R Do not keep the KEYLESS-GO key together
with:
- electronic devices, e.g. a mobile phone
or another key
- metallic objects, e.g. coins or metal foil.
This can affect the functionality of
KEYLESS-GO.
R When locking and unlocking using
KEYLESS-GO, the distance between the
SmartKey and the corresponding door
handle must not exceed 3 ft (1 m).
R If the KEYLESS-GO key is removed from the
vehicle, it is possible that the system may
not recognize the SmartKey. The vehicle
can then not be locked or started using
KEYLESS-GO.
R If the KEYLESS-GO key has been removed
from the vehicle, e.g. if a passenger leaves
the vehicle with a KEYLESS-GO key:
- if the start/stop button is pressed or if
an attempt is made to lock the vehicle
with the locking button on the outer door
handle, the Key Not Detected message
appears in the multifunction display
- when the engine is running, the red Key
Not Detected message appears in the
multifunction display as you pull away.
Find the KEYLESS-GO key and change its
position in the vehicle. Carry the
KEYLESS-GO key in your shirt pocket, for
example.
R If you have started the engine with the
Start/Stop button, you can switch it off
again by:
- pressing the Start/Stop button again
- inserting the KEYLESS-GO key into the
ignition lock if the vehicle is stationary
and the automatic transmission is in park
position P.
R You could unlock the vehicle by mistake if
the distance between the KEYLESS-GO key
and the vehicle is less than 3 ft (1 m) and:
- an exterior door handle is hit by a water
jet
or
- you clean an exterior door handle.
R Bear in mind that the engine can be started
by any of the vehicle occupants if there is
a KEYLESS-GO key in the vehicle.72SmartKeyOpening/closing

X To unlock the vehicle: touch the inner
surface of the door handle.XTo lock the vehicle: touch sensor
surface :.XConvenience closing feature: touch
recessed sensor surface ; for an
extended period ( Y page 85).
If you pull on the handle of the trunk lid, only
the trunk of the vehicle is unlocked.
Changing the settings of the locking
system
You can change the setting of the locking
system in such a way that only the driver's
door and the fuel filler flap are unlocked. This
is useful if you frequently travel on your own.
XTo change the setting: press and hold
down the % and & buttons
simultaneously for approximately six
seconds until the battery check lamp
( Y page 74) flashes twice.
i
If the setting of the locking system is
changed within the signal range of the
vehicle, pressing the & or % button
locks or unlocks the vehicle.
The SmartKey now functions as follows:
XTo unlock the driver's door: press the
% button once.XTo unlock centrally: press the %
button twice.XTo lock centrally: press the & button.
The KEYLESS-GO function is changed as
follows:
XTo unlock the driver's door: touch the
inner surface of the door handle on the
driver's door.XTo unlock centrally: touch the inner
surface of the door handle on the front-
passenger door or the rear door.XTo lock centrally: touch the outer sensor
surface on one of the door handles.Restoring the factory settingsXPress the % and & buttons
simultaneously for approximately six
seconds until the battery check lamp
flashes twice.
Mechanical key
General notes
If the vehicle can no longer be locked or
unlocked with the SmartKey, use the
mechanical key.
If you use the mechanical key to unlock and
open the driver's door or the trunk lid, the
anti-theft alarm system will be triggered
( Y page 67).
There are several ways to turn off the alarm:
XTo turn the alarm off with the
SmartKey: press the % or & button
on the SmartKey.
or
XInsert the SmartKey into the ignition lock.
or
XTo deactivate the alarm with KEYLESS-
GO: press the Start/Stop button in the
ignition lock. The SmartKey must be in the
vehicle.
or
XLock or unlock the vehicle using KEYLESS-
GO. The SmartKey must be outside the
vehicle.
If you unlock the vehicle using the mechanical
key, the fuel filler flap will not be unlocked
automatically.
XTo unlock the fuel filler flap: insert the
SmartKey in the ignition lock.SmartKey73Opening/closingZ

Removing the mechanical keyXPush release catch : in the direction of
the arrow and at the same time, remove
mechanical key ; from the SmartKey.
SmartKey battery
Important safety notes
Have the batteries changed at a qualified
specialist workshop.
GWARNING
Batteries contain toxic substances.
Swallowing batteries can lead to serious
health issues or death.
Keep batteries out of the reach of children.
Seek medical attention immediately if a
battery is swallowed.
GWARNING
The SmartKey batteries contain perchlorate
material, which may require special handling
and regard for the environment. Observe
government disposal guidelines. California
residents, see www.dtsc.ca.gov/
HazardousWaste/Perchlorate/
index.cfm .
Checking the batteryXPress the & or % button.
The battery is working properly if battery
check lamp : lights up briefly
If battery check lamp : does not light up
briefly during the test, the battery is
discharged.
XChanging the battery ( Y page 74)
i
You can obtain the battery at a qualified
specialist workshop.
i If the SmartKey battery is checked within
the signal reception range of the vehicle,
pressing the & or % button locks or
unlocks the vehicle.
Changing the battery
You require a CR 2025 3 V cell battery.
XTake the mechanical key out of the
SmartKey ( Y page 73).XPress mechanical key ; into the opening
in the SmartKey in the direction of the74SmartKeyOpening/closing

Problems with the SmartKeyProblemPossible causes/consequences and M SolutionsYou cannot lock or
unlock the vehicle
using the SmartKey.The SmartKey battery is discharged or nearly discharged.XTry again to lock/unlock the vehicle using the remote control
function of the SmartKey. Point the tip of the SmartKey at the
driver's door handle from close range and press the %/
& button.
If this does not work:
XCheck the SmartKey battery ( Y page 74) and replace it if
necessary ( Y page 74).XLock ( Y page 79) or unlock ( Y page 79) the vehicle using
the mechanical key.The SmartKey is faulty.XLock ( Y page 79) or unlock ( Y page 79) the vehicle using
the mechanical key.XHave the SmartKey checked at a qualified specialist workshop.You can no longer lock
or unlock the vehicle
using KEYLESS-GO.There is interference from a powerful source of radio waves.XLock/unlock the vehicle using the remote control function of
the SmartKey. Point the tip of the SmartKey at the driver's door
handle from close range and press the %/& button.There is a malfunction with KEYLESS-GO.XLock/unlock the vehicle using the remote control function of
the SmartKey. Point the tip of the SmartKey at the driver's door
handle from close range and press the %/& button.XHave KEYLESS-GO checked at a qualified specialist workshop.
If this does not work:
XCheck the SmartKey battery ( Y page 74) and replace it if
necessary ( Y page 74).XLock ( Y page 79) or unlock ( Y page 79) the vehicle using
the mechanical key.You have lost a
SmartKey.XHave the SmartKey deactivated at a qualified specialist
workshop.XReport the loss immediately to the vehicle insurers.XIf necessary, have the locks changed as well.You have lost the
mechanical key.XReport the loss immediately to the vehicle insurers.XIf necessary, have the locks changed as well.76SmartKeyOpening/closing

SmartKeyDisplay messagesPossible causes/consequences and M SolutionsÂ
Key Does Not
Belong to VehicleYou have put the wrong SmartKey in the ignition lock.XUse the correct SmartKey.Â
Take Your Key from
IgnitionThe SmartKey is in the ignition lock.XRemove the SmartKey.Â
Obtain a New KeyThe SmartKey needs to be replaced.XVisit a qualified specialist workshop.Â
Replace Key BatteryThe batteries of the KEYLESS-GO key are discharged.XChange the batteries ( Y page 74).Â
Don't Forget Your
KeyThe display message is shown for a maximum of 60 seconds and
is only a reminder.
You have opened the driver's door with the engine switched off.
The KEYLESS-GO key is not in the ignition lock.XRemember to take the KEYLESS-GO key with you when you
leave the vehicle.Â
Key Not Detected
(red display message)The KEYLESS-GO 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.XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.XApply the parking brake.XLocate the KEYLESS-GO key.The KEYLESS-GO key is not detected while the engine is running
because there is interference from a strong source of radio waves.
A warning tone also sounds.XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.XEngage the parking brake.XOperate the vehicle with the SmartKey in the ignition lock.238Display messagesOn-board computer and displays