Engine MERCEDES-BENZ R-Class 2012 W251 Owner's Guide

Trailers with a high center of gravity may tip
over before the system recognizes swaying of
the trailer.
Trailer stabilization does not work if ESP ®
is
deactivated or disengaged because of a
malfunction.
EBD (electronic brake force
distribution)
i Observe the "Important safety notes"
section ( Y page 64).
EBD monitors and controls the brake
pressure on the rear wheels to improve
driving stability while braking.
GWARNING
If EBD has malfunctioned, the braking system
remains available with full brake boosting
effect. However, the rear wheels can still lock,
e.g. under full braking. This could cause you
to lose control of your vehicle and cause an
accident. You should therefore adapt your
driving style to the different handling
characteristics.
XObserve the notes on warning and indicator
lamps ( Y page 240) as well as display
messages ( Y page 216).
Distance warning function (vehicles
with DISTRONIC)
This function provides a warning from a speed
of approximately 20 mph(30 km/h), if:
R for a period of several seconds, the
distance to the vehicle in front is too short
for the speed at which you are traveling.
The · distance warning lamp in the
instrument cluster will light up.
R you are rapidly approaching the vehicle in
front. An intermittent warning tone will
then sound and the · distance warning
lamp will light up in the instrument cluster.
You must apply the brakes yourself in order
to maintain the appropriate distance to the
vehicle in front and prevent a collision.GWARNING
If the distance warning lamp · in the
instrument cluster comes on while driving
and/or an intermittent warning sounds,
immediate attention on the part of the driver
is required. As required by the traffic
situation, apply the brakes and navigate
around a possible obstacle. However, do not
drive by relying on the distance warning
function, as this will result in an emergency
braking application. This will not always
enable you to avoid a collision, especially
when traveling on varying road surface
conditions and with varying driver reaction.
Complex driving situations are not always
fully recognized by the distance warning
function. This could result in wrong or missing
distance warnings.
XTo activate/deactivate: activate or
deactivate the distance warning function in
the on-board computer ( Y page 210).
After activation, the Ä symbol is
displayed in the lower multifunction
display.
Theft deterrent locking systems
Immobilizer
The immobilizer prevents your vehicle from
being started without the correct SmartKey.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. The
engine can be started by anyone with a valid
SmartKey that is left inside the vehicle.
XTo activate with the SmartKey: remove
the SmartKey from the ignition lock.XTo activate with KEYLESS-GO: switch the
ignition off and open the driver's door.XTo deactivate: switch on the ignition.68Theft deterrent locking systemsSafety

iThe immobilizer is always deactivated
when you start the engine.
In the event that the engine cannot be
started when the starter battery is fully
charged, the immobilizer may be faulty.
Contact an authorized Mercedes-Benz
Center or call 1-800-FOR-MERCedes (in
USA) or 1-800-387-0100 (in Canada).
ATA (Anti-Theft Alarm system)
A visual and audible alarm is triggered if the
alarm system is armed and you open:
R a door
R the vehicle with the mechanical key
R the tailgate
R the hood
The alarm is not switched off, even if you
close the open door that has triggered it, for
example.
i If the alarm stays on for more than 30
seconds, the emergency call system
mbrace (USA only) or TELE AID (Canada
only) initiates a call to the Customer
Assistance Center automatically. The
emergency call system initiates the call
provided that:
R you have subscribed to the mbrace/
TELE AID service.
R the mbrace/TELE AID service has been
activated properly.
R the required mobile phone, power supply
and GPS are available.
XTo arm: lock the vehicle with the SmartKey
or KEYLESS-GO.
Indicator lamp : flashes. The alarm
system is armed after approximately 10
seconds.XTo deactivate: unlock the vehicle with the
SmartKey or KEYLESS-GO.XTo stop the alarm using the SmartKey:
insert the SmartKey into the ignition lock.
The alarm is switched off.
or
XPress the % or & button on the
SmartKey.
The alarm is switched off.XTo stop the alarm using KEYLESS-GO:
grasp the outside door handle. The
SmartKey must be outside the vehicle.
The alarm is switched off.
or
XPress the Start/Stop button on the
dashboard. The SmartKey must be inside
the vehicle.
The alarm is switched off.Theft deterrent locking systems69SafetyZ

Useful information
i This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences are
possible. Please note that your vehicle may
not be equipped with all features
described. This also applies to safety-
related systems and functions.
i Please read the information on qualified
specialist workshops ( Y page 24).
SmartKey
Important safety notes
GWARNING
When leaving the vehicle, always remove the
SmartKey from the ignition lock. Always take
the SmartKey with you and lock the vehicle.
Do not leave children unsupervised in the
vehicle, even if they are secured in a child
restraint system, and do not give them access
to an unlocked vehicle. A child's unsupervised
access to a vehicle could result in an accident
and/or serious personal injury. They could:
R injure themselves on vehicle parts
R be seriously or fatally injured by extreme
heat or cold
R injure themselves or have an accident with
vehicle equipment that may still be in
operation even after the SmartKey has
been removed from the ignition, such as the
seat adjustment, steering wheel
adjustment or memory function.
If children open a door, they could cause
severe or even fatal injury to other persons; if
they get out of the vehicle, they could injure
themselves when doing so or be seriously or
even fatally injured by any passing traffic.
Do not expose the child restraint system to
direct sunlight. The child restraint system's
metal parts, for example, could become very
hot, and a child could be burned on these
parts.GWARNING
If a key ring is too heavy or too large, the
weight acting on the key could cause it to turn
in the ignition lock or catch on the steering
wheel. This could cause the engine to be
switched off suddenly. You could lose control
of the vehicle and cause an accident. Do not
attach any heavy or large key rings to the key
that is inserted in the ignition.
General information
If you cannot lock or unlock the vehicle with
the SmartKey, either the battery in the
SmartKey is discharged, the SmartKey is
faulty or the starter battery is discharged.
XCheck the battery in the SmartKey and
replace it if necessary ( Y page 76).XUnlock the driver's door using the
mechanical key ( Y page 81).XLock the vehicle ( Y page 81).XHave the starter battery and battery
contacts checked at an authorized
Mercedes-Benz Center.
If the SmartKey is faulty, contact Roadside
Assistance or an authorized Mercedes-Benz
Center.
SmartKey functions
General notes
i USA only:
This device complies with Part 15 of the
FCC Rules. 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.
72SmartKeyOpening/closing

2. this device must accept any interference
received, including interference that may
cause undesired operation of the device.
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 vehicle is parked for more than
72 hours, the KEYLESS-GO function is
deactivated. Pull the outer door handle and
switch on the ignition to reactivate the
KEYLESS-GO function.
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
- while the engine is running, the red Key
Not Detected message will appear 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.74SmartKeyOpening/closing

ProblemPossible causes/consequences and M SolutionsYou have lost the
mechanical key.XReport the loss immediately to the vehicle insurers.XIf necessary, have the locks changed as well.The engine cannot be
started using the
SmartKey.The on-board voltage is too low.XSwitch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work:
XCheck the starter battery and charge it if necessary
( Y page 310).
or
XJump-start the vehicle ( Y page 313).
or
XConsult a qualified specialist workshop.The engine cannot be
started using KEYLESS-
GO. The SmartKey is in
the vehicle.A door is open. Therefore, the SmartKey cannot be detected as
easily.XClose the door and try to start the vehicle again.There is interference from a powerful source of radio waves.XStart your vehicle with the SmartKey in the ignition lock.Doors
Important safety notes
GWARNING
When leaving the vehicle, always remove the
SmartKey from the ignition lock. Always take
the SmartKey with you and lock the vehicle.
Do not leave children unsupervised in the
vehicle, even if they are secured in a child
restraint system, and do not give them access
to an unlocked vehicle. A child's unsupervised
access to a vehicle could result in an accident
and/or serious personal injury. They could:
R injure themselves on vehicle parts
R be seriously or fatally injured by extreme
heat or cold
R injure themselves or have an accident with
vehicle equipment that may still be in
operation even after the SmartKey has
been removed from the ignition, such as the
seat adjustment, steering wheel
adjustment or memory function.
If children open a door, they could cause
severe or even fatal injury to other persons; if
they get out of the vehicle, they could injure
themselves when doing so or be seriously or
even fatally injured by any passing traffic.
Do not expose the child restraint system to
direct sunlight. The child restraint system's
metal parts, for example, could become very
hot, and a child could be burned on these
parts.GWARNING
Do not carry heavy or hard objects in the
passenger compartment or cargo
compartment unless they are firmly secured
in place.
Doors79Opening/closingZ

GWARNING
When leaving the vehicle, always remove the
SmartKey from the ignition lock. Always take
the SmartKey with you and lock the vehicle.
Do not leave children unsupervised in the
vehicle, even if they are secured in a child
restraint system, and do not give them access
to an unlocked vehicle. A child's unsupervised
access to a vehicle could result in an accident
and/or serious personal injury. They could:
R injure themselves on vehicle parts
R be seriously or fatally injured by extreme
heat or cold
R injure themselves or have an accident with
vehicle equipment that may still be in
operation even after the SmartKey has
been removed from the ignition, such as the
seat adjustment, steering wheel
adjustment or memory function.
If children open a door, they could cause
severe or even fatal injury to other persons; if
they get out of the vehicle, they could injure
themselves when doing so or be seriously or
even fatally injured by any passing traffic.
Do not expose the child restraint system to
direct sunlight. The child restraint system's
metal parts, for example, could become very
hot, and a child could be burned on these
parts.
GWARNING
Do not carry heavy or hard objects in the
passenger compartment or cargo
compartment unless they are firmly secured
in place.
Unsecured or improperly positioned cargo
increases a child's risk of injury in the event
of
R strong braking maneuvers
R sudden changes of direction
R an accident
GWARNING
Make sure the tailgate is closed when the
engine is running and while driving. Among
other dangers, deadly carbon monoxide (CO)
gases may enter vehicle interior resulting in
unconsciousness and death.
! The tailgate swings upwards and to the
rear when opened. Therefore, make sure
that there is sufficient clearance above and
behind the tailgate.
To open the tailgate completely, a minimum
clearance of 7.20 ft (2.20 m) above the
ground is necessary.
You can:
R open and close the tailgate manually from
outside
R open and close the tailgate automatically
from outside
R open and close the tailgate automatically
from inside
R open the tailgate manually from inside
R limit the opening angle of the tailgate
Opening/closing from the outside
Opening
XPress the % button on the SmartKey.XPull handle :.XRaise the tailgate.
Closing
GWARNING
To prevent possible personal injury, always
keep hands and fingers away from the cargo
82Cargo compartmentOpening/closing

compartment opening when closing the
tailgate. Be especially careful when small
children are around.XPull the tailgate down using recess :.XPush the tailgate closed from outside the
vehicle.XIf necessary, lock the vehicle with
the & button on the SmartKey
( Y page 72) or with KEYLESS-GO
( Y page 73).
i
If a KEYLESS-GO key is detected in the
cargo compartment, the tailgate will not
lock.
Opening/closing automatically from
outside
Important safety notes
GWARNING
Make sure the tailgate is closed when the
engine is running and while driving. Among
other dangers, deadly carbon monoxide (CO)
gases may enter vehicle interior resulting in
unconsciousness and death.
! The tailgate swings upwards and to the
rear when opened. Therefore, make sure
that there is sufficient clearance above and
behind the tailgate.
To open the tailgate completely, a minimum
clearance of 7.20 ft (2.20 m) above the
ground is necessary.
Opening
You can open the tailgate automatically using
the SmartKey or the handle in the tailgate.
XPress and hold the F button on the
SmartKey until the tailgate opens.
or
XWhen the tailgate is unlocked, pull the
handle and let it go again immediately.
Closing
GWARNING
Monitor the closing procedure carefully to
make sure no one is in danger of being
injured. To prevent possible personal injury,
always keep hands and fingers away from the
cargo compartment opening when closing the
tailgate. Be especially careful when small
children are around. To stop the closing
procedure, do one of the following:
R Press or pull the remote tailgate opening/
closing switch on the driver's door.
R Press the tailgate closing switch.
R Press the KEYLESS-GO locking/closing
switch.
R Pull outside handle on the tailgate.
R When no SmartKey is inserted in the starter
switch (vehicles with KEYLESS-GO: Make
sure the vehicle's on-board electronics
have status 0): Press button F on the
SmartKey.
You can close the tailgate automatically using
the SmartKey, the closing button 5
or the
locking button 6
.
5 For vehicles with the EASY-PACK tailgate only.
6 For vehicles with the EASY-PACK tailgate and KEYLESS-GO only.Cargo compartment83Opening/closingZ

Closing button and locking button (example:
vehicle with the EASY-PACK tailgate and KEYLESS-
GO)
XTo close: press closing button : on the
tailgate.
or
XPress and hold the F button on the
SmartKey until the tailgate closes.XTo close and lock simultaneously:
Press locking button ; on the tailgate.
i
The tailgate can only be opened and
closed with the SmartKey if there is no
SmartKey in the ignition lock.
If the tailgate touches an object while
closing, the closing procedure is
interrupted and the tailgate reopens.
i If you leave a KEYLESS-GO key in the
cargo compartment, the tailgate will not
lock.
The tailgate is not closed unless a
KEYLESS-GO key is detected.
Opening/closing automatically from
the inside
GWARNING
Maintain sight of the area around the rear of
the vehicle while operating the tailgate with
the door-mounted remote tailgate switch.
Monitor the opening procedure carefully to
make sure no one is in danger of being
injured.
To interrupt the opening procedure, press or
pull the door-mounted remote tailgate switch.
When the SmartKey is not inserted in the
starter switch (vehicles with KEYLESS-GO:
Make sure the vehicle's on-board electronics
have status 0): Press button F on the
SmartKey.GWARNING
Maintain sight of the area around the rear of
the vehicle while operating the tailgate with
the door-mounted remote tailgate switch.
Monitor the closing procedure carefully to
make sure no one is in danger of being
injured.
To interrupt the closing procedure, press or
pull the door-mounted remote tailgate switch.
GWARNING
To prevent possible personal injury, always
keep hands and fingers away from the cargo
compartment opening when closing the
tailgate. Be especially careful when small
children are around.
GWARNING
Make sure the tailgate is closed when the
engine is running and while driving. Among
other dangers, deadly carbon monoxide (CO)
gases may enter vehicle interior resulting in
unconsciousness and death.
You can open and close the tailgate from the
driver's seat when the vehicle is stationary
and unlocked.
84Cargo compartmentOpening/closing

automatic operation by operating the
switch again.
i You can continue to operate the side
windows after you switch off the engine or
remove the SmartKey. This function is
available for up to five minutes or until the
driver's or front-passenger door is opened.
Opening and closing the hinged side
windows
The hinged side windows are operated
electrically from the from the driver's seat.
GWARNING
Make sure that nobody can become trapped
as you close the hinged side windows. If there
is a risk of somebody becoming trapped,
release the switch or push the switch again to
reopen the side window.
Door control panel
XMake sure that the SmartKey is in position
1 or 2 in the ignition lock.XTo open fully: press switch : and release.XTo close fully: pull switch : and release.XTo stop the closing procedure: press
switch : again.
Both hinged side windows open fully.
i If the hinged side windows are blocked
when closing, the closing procedure is
terminated and the hinged side windows
open again slightly.
i For safety reasons, the hinged side
windows can only be opened again after
four seconds.
Convenience opening feature
You can ventilate the vehicle before you start
driving. To do this, the key is used to carry out
the following functions simultaneously:
R unlock the vehicle
R open the side windows
R open the hinged side windows
R open the sliding sunroof or the panorama
roof with power tilt/sliding panel and the
roller sunblinds
i The convenience opening feature can
only be operated using the SmartKey. The
SmartKey must be close to the driver's
door handle.
XPoint the tip of the SmartKey at the driver's
door handle.XPress and hold the % button until the
side windows and the sliding sunroof or the
panorama roof with power tilt/sliding
panel are in the desired position.
If the roller sunblinds of the panorama roof
with power tilt/sliding panel are closed, the
roller sunblinds are opened first.
XPress and hold the % button again until
the panorama roof with power tilt/sliding
panel is in the desired position.XTo interrupt convenience opening:
release the % button.Side windows87Opening/closingZ

The opening/closing procedure of the sliding
sunroof can be immediately halted by
releasing the sliding sunroof switch or, if the
sliding sunroof switch was moved past the
resistance point and released, by moving the
sliding sunroof switch in any direction.GWARNING
The sliding sunroof is made out of glass. In the
event of an accident, the glass may shatter.
This may result in an opening in the roof.
In a vehicle rollover, occupants not wearing
their seat belts or not wearing them properly
may be thrown out of the opening. Such an
opening also presents a potential for injury for
occupants wearing their seat belts properly,
as entire body parts or portions of them may
protrude from the passenger compartment.
! Only open the sliding sunroof if it is free
of snow and ice. Otherwise, malfunctions
may occur.
Do not allow anything to protrude from the
sliding sunroof. Otherwise, the seals could
be damaged.
! The weather can change abruptly. It could
start to rain or snow. Make sure that the
sliding sunroof is closed when you leave the
vehicle. The vehicle electronics can be
damaged if water enters the vehicle
interior.
i Resonance noises can occur in addition
to the usual airflow noises when the sliding
sunroof is open. They are caused by minor
pressure fluctuations in the vehicle interior.
Change the position of the sliding sunroof
or open a side window slightly to reduce or
eliminate these noises.
Operating the sliding sunroof
Opening and closing
i You can continue to operate the sliding
sunroof after switching off the engine or
removing the SmartKey from the ignition
lock. This function is available for up to five
minutes or until the driver's or front-
passenger door is opened.
Overhead control panel
:To raise;To open=To close/lowerXTurn the SmartKey to position 1 or 2 in the
ignition lock.XPress or pull the 2 switch in the
corresponding direction.
i If you press the 2 switch beyond the
point of resistance, an automatic opening/
closing process is started in the
corresponding direction. You can stop
automatic operation by operating the
switch again.
The sun protection cover automatically opens
along with the sliding sunroof. You can open
or close the sun protection cover manually
when the sliding sunroof is raised or closed.
Resetting
Reset the sliding sunroof if it does not move
smoothly, or if the battery has been
disconnected or has become discharged.
XRemove the SmartKey from the ignition
lock or select position 0 (KEYLESS-GO).XRemove the fuse for the sliding sunroof
from the fuse box. To find out where the
fuse is located, refer to the fuse allocation
chart in the vehicle tool kit ( Y page 296).XReinsert the fuse.90Sliding sunroofOpening/closing