Engine MERCEDES-BENZ R-Class 2012 W251 User Guide

Product information
Mercedes-Benz recommends that you use
genuine Mercedes-Benz parts, conversion
parts and accessories that have been
approved for the type of vehicle.
Mercedes-Benz tests genuine parts as well as
conversion parts and accessories which have
been specifically approved for your vehicle for
their reliability, safety and suitability. Despite
ongoing market research, Mercedes-Benz is
unable to assess other parts. Therefore,
Mercedes-Benz accepts no responsibility for
the use of such parts in Mercedes-Benz
vehicles, even if they have been
independently or officially approved. The use
of non-approved parts could affect your
vehicle's operating safety. Mercedes-Benz
therefore recommends that you use genuine
Mercedes-Benz parts, conversion parts and
accessories that have been approved for the
type of vehicle. Genuine Mercedes-Benz
parts, approved conversion parts and
accessories are available from any authorized
Mercedes-Benz Center. Here, you will receive
advice about permissible technical
modifications, and the parts will be
professionally installed.
Operator's Manual
Notes on the Operator's Manual
This Operator's Manual contains a great deal
of helpful information. We urge you to read it
carefully and familiarize yourself with the
vehicle before driving.
For your own safety and longer service life of
the vehicle, we urge you to follow the
instructions and warnings contained in this
Operator's Manual. Ignoring them could
result in damage to the vehicle or personal
injury to you or others. Vehicle damage
caused by failure to follow instructions is not
covered by the Mercedes-Benz Limited
Warranty.
Vehicle equipment
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. The equipment in your vehicle may
therefore differ from that shown in the
descriptions and illustrations. All the systems
found in your vehicle are listed in the original
purchase agreement of your vehicle. Should
you have any questions concerning
equipment and operation, please consult an
authorized Mercedes-Benz Center.
The Operating Instructions and the
Maintenance Booklet are important
documents and should be kept in the vehicle.
Service and vehicle operation
Service and literature
Your vehicle is covered under the terms of the
warranties printed in the Service and
Warranty Information booklet. Your
authorized Mercedes-Benz Center will
exchange or repair any defective parts
originally installed in the vehicle in
accordance with the terms of the following
warranties:
R New Vehicle Limited Warranty
R Emission Systems Warranty
R Emission Performance Warranty
R California, Connecticut, Maine,
Massachusetts, New York, Pennsylvania,
Rhode Island and Vermont Emission
Control System Warranty 2
R California, Connecticut, Maine,
Massachusetts, New York, Pennsylvania,
2 Valid only for vehicles with a gasoline engine.Introduction21

Change of address or ownership
In the event of a change of address, please
send us the "Change of Address Notice"
found in the Service and Warranty
Information Booklet, or simply call the
Mercedes-Benz Customer Assistance Center
(in the USA) at the hotline number
1-800-FOR-MERCedes(1-800-367-6372) or
Customer Service Center (in Canada) at
1-800-387-0100. This will assist us in
contacting you in a timely manner should the
need arise.
If you sell your Mercedes, please leave the
entire literature in the vehicle so that it is
available to the next owner.
If you bought this vehicle used, be sure to
send in the "Notice of Purchase of Used
Truck" found in the Service and Warranty
Information Booklet, or call the Mercedes-
Benz Customer Assistance Center (in the
USA) at
1-800-FOR-MERCedes(1-800-367-6372) or
Customer Service (in Canada) at
1-800-387-0100.
Vehicle operation outside the USA
and Canada
If you plan to operate your vehicle in foreign
countries, please be aware that:
R service facilities or replacement parts may
not be readily available.
R unleaded fuel for vehicles with a catalytic
converter may not be available. Leaded fuel
may cause damage to the catalytic
converter.
R the fuel may have a considerably lower
octane rating. Unsuitable fuel can cause
engine damage.
Operating safety
Safety notes
GWARNING
Work improperly carried out on electronic
components and associated software could
cause them to cease functioning. Because the
vehicle's electronic components are
interconnected, any modifications made may
produce an undesired effect on other
systems. Electronic malfunctions could
seriously impair the operating safety of your
vehicle.
Contact an authorized Mercedes-Benz Center
for repairs or modifications to electronic
components.
Other improper work or modifications on the
vehicle could also have a negative impact on
the operating safety of the vehicle.
Some safety systems only function when the
engine is running. You should therefore never
turn off the engine while driving.
GWARNING
Heavy blows against the vehicle underbody or
tires/wheels may cause serious damage and
impair the operating safety of your vehicle.
Such blows can be caused, for example, by
running over an obstacle, road debris or a
pothole.
If you feel a sudden significant vibration or
ride disturbance, or you suspect that damage
to your vehicle has occurred:
R turn on your hazard warning flashers.
R slow down carefully.
R drive with caution to an area which is a safe
distance from the road.
Inspect the vehicle underbody and tires/
wheels for possible damage. If the vehicle
appears unsafe, have it towed to the nearest
authorized Mercedes-Benz Center or other
qualified maintenance or repair facility for
further inspection or repairs.
Introduction23Z

Warning and indicator lampsFunctionPage:ABS240;The lamp lights up briefly,
but has no function.=Brakes (USA only)239?ESP ®241ADistance warning signal245On vehicles without
DISTRONIC, the lamp lights
up briefly but has no
function.BBrakes (Canada only)239CTire pressure monitor (USA
only)
245
FunctionPageDTurn signal117EESP ®
OFF241FSeat belt238GDiesel engine: preglow146HSRS243ILow-beam headlamps115JCheck Engine (Canada
only)
244
KCheck Engine (USA only)244LHigh-beam headlamps117MReserve fuel24430Instrument clusterAt a glance

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).
Occupant safety
Overview of occupant safety
In this section, you will learn the most
important facts about the restraint system
components of the vehicle.
The restraint system consists of:
R seat belts
R child restraint systems
R LATCH-type (ISOFIX) child seat anchors
Additional protection is provided by:
R SRS (Supplemental Restraint System)
R NECK-PRO head restraints/NECK-PRO
luxury head restraints
R PRE-SAFE ®
R Air bag system components with:
- PASSENGER AIR BAG OFF indicator lamp
- front-passenger seat with Occupant
Classification System (OCS)
The different air bag systems work
independently of each other. The protective
functions of the system work in conjunction
with each other. Not all air bags are deployed
in an accident.
GWARNING
Modifications to or work improperly
conducted on restraint system components
or their wiring, as well as tampering with
interconnected electronic systems, can lead
to the restraint systems no longer functioning
as intended.
Air bags or Emergency Tensioning Devices
(ETDs), for example, could deploy
inadvertently or fail to deploy in accidents
although the deceleration threshold for air
bag deployment is exceeded. Therefore,
never modify the restraint systems. Do not
tamper with electronic components or their
software.
i See "Children in the vehicle"
( Y page 56) for more information on
infants and children traveling with you in
the vehicle and restraints for infants and
children.
SRS (Supplemental Restraint System)
Introduction
SRS consists of:
R the + SRS warning lamp
R air bags
R air bag control unit (with crash sensors)
R Emergency Tensioning Devices
R belt force limiters
SRS reduces the risk of occupants coming
into contact with the vehicle's interior in the
event of an accident. It can also reduce the
effect of the forces to which occupants are
subjected during an accident.
SRS warning lamps
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 instrument
cluster lights up when the ignition is switched
on. It goes out no later than a few seconds
after the engine is started.
38Occupant safetySafety

The SRS components are in operational
readiness when the + SRS warning lamp
is not lit while the engine is running .GWARNING
The SRS self-check has detected a
malfunction if the + SRS warning lamp:
R does not come on at all
R fails to go out approximately 4 seconds
after the engine was started
R comes on after the engine was started or
while driving
For your safety, Mercedes-Benz strongly
recommends that you have the system
checked as soon as possible at an authorized
Mercedes-Benz Center. Otherwise the SRS
may not be activated when it is needed in an
accident, which could result in serious or fatal
injury. The SRS might also deploy
unexpectedly and unnecessarily which could
also result in injury.
In addition, improper work on the SRS creates
a risk of rendering the SRS inoperative or
causing unintended air bag deployment. Work
on the SRS must therefore only be performed
by qualified technicians. Contact an
authorized Mercedes-Benz Center.
If it is necessary to modify an air bag system
to accommodate a person with disabilities,
contact an authorized Mercedes-Benz Center
for details. USA only: Call our Customer
Assistance Center at 1-800-FOR-MERCedes
(1-800-367-6372) for details.
Safety guidelines for seat belts,
Emergency Tensioning Devices (ETDs)
and air bags
GWARNING
R Damaged seat belts or seat belts that have
been subjected to stress in an accident
must be replaced. Their anchoring points
must also be checked. Only use seat belts
installed or supplied by an authorized
Mercedes-Benz Center.
R Air bags and pyrotechnic Emergency
Tensioning Devices (ETDs) contain
perchlorate material, which may require
special handling and regard for the
environment. Check your national disposal
guidelines. California residents, see
www.dtsc.ca.gov/HazardousWaste/
Perchlorate/index.cfm .
R Air bags and ETDs are designed to function
on a one-time-only basis. An air bag or ETD
that has deployed must be replaced. PRE-
SAFE ®
has electrically operated reversible
belt tensioners in addition to the
pyrotechnic ETDs.
R Do not pass seat belts over sharp edges.
They could tear.
R Do not make any modification that could
change the effectiveness of the seat belts.
R Do not bleach or dye seat belts as this may
severely weaken them. In a crash they may
not be able to provide adequate protection.
R No modifications of any kind may be made
to any components or wiring of the SRS.
R Do not change or remove any component
or part of the SRS.
R Do not install additional trim material, seat
covers, badges, etc. to the:
- padded steering wheel boss
- front-passenger air bag cover
- outer side of front seat bolsters
- outer side of the seat bolsters of the rear
bench seat backrest
- roof lining trim
R Do not install additional electrical/
electronic equipment on or near SRS
components and wiring.
R Keep area between air bags and occupants
free of objects (e.g. packages, purses,
umbrellas, etc.).
R Do not hang items such as coat hangers
from the coat hooks or handles over the
door. These items may be thrown around inOccupant safety39SafetyZ

being up to or less than the weight of a typical
12-month-old child in a standard child
restraint, the 42 indicator lamp
will illuminate when the engine is started and
remain illuminated. This indicates that the
front passenger front air bag is deactivated.
When the OCS senses that the front
passenger seat is classified as being empty,
the 42 indicator lamp will
illuminate when the engine is started and
remain illuminated. This indicates that the
front passenger front air bag is deactivated.
When the OCS senses that the front
passenger seat occupant is classified as
being heavier than the weight of a typical 12-
month-old child seated in a standard child
restraint or as being a small individual (such
as a young teenager or a small adult), the
42 indicator lamp will illuminate
for approximately 6 seconds when the engine
is started. Depending on occupant weight
sensor readings from the seat, it will then
remain illuminated or go out. With the
42 indicator lamp illuminated,
the front passenger front air bag is
deactivated. With the 42
indicator lamp out, the front passenger front
air bag is activated.
When the OCS senses that the front
passenger seat occupant is classified as an
adult or someone larger than a small
individual, the 42 indicator lamp
will illuminate for approximately six seconds
when the engine is started and then go out.
This indicates that the front passenger front
air bag is activated.
If the 42 indicator lamp is
illuminated, the front passenger front air bag
is deactivated and will not be deployed.If the 24 indicator lamp is not
illuminated, the front passenger front air bag
is activated and will be deployed
R in the event of certain frontal impacts
R if the impact exceeds a predetermined
triggering threshold
R independently of the side impact air bags
If the front passenger front air bag is
deployed, the rate of inflation will be
influenced by
R the rate of vehicle deceleration as assessed
by the air bag control unit
R the front passenger's weight category as
identified by the OCS
For further information, see "air bag display
messages" ( Y page 220).GWARNING
According to accident statistics, children are
safer when properly restrained on the rear
seats than on the front-passenger seat. Thus,
we strongly recommend that children be
placed in the rear seats whenever possible.
Regardless of seating position, children 12
years old and under must be seated and
properly secured in an appropriately sized
child restraint system or booster seat
recommended for the size and weight of the
child.
The infant or child restraint system must be
properly secured with the vehicle's seat belt,
the seat belt and Top Tether strap, or lower
anchors and Top Tether strap, fully in
accordance with the child seat
manufacturer's instructions.
Occupants, especially children, should always
sit as upright as possible, wear the seat belt
properly and use an appropriate sized infant
restraint, toddler restraint, or booster seat
recommended for the size and weight of the
child.
Occupant safety45SafetyZ

For more information about releasing the seat
belt with release button ?, see "Releasing
seat belts" ( Y page 54).
Seat belt adjustment
The seat-belt adjustment function adjusts the
driver's and front-passenger seat belt to the
upper body of the occupants.
The belt strap is tightened slightly when:
R you engage the belt tongue in the belt
buckle and you then turn the SmartKey to
position 2 in the ignition lock.
R the SmartKey is in position 2 in the ignition
lock and you then engage the belt tongue
in the buckle.
The seat-belt adjustment will apply a
retraction force if any slack is detected
between the occupant and the seat belt. Do
not hold on to the seat belt tightly while it is
adjusting. You can switch the seat-belt
adjustment on and off in the on-board
computer ( Y page 209).
The seat-belt adjustment is an integral part of
the PRE-SAFE ®
convenience function. More
information about PRE-SAFE ®
can be found
in the "PRE-SAFE ®
(preventative occupant
protection)" section ( Y page 49).
Belt height adjustment
You can adjust the seat belt height on the
driver's seat and the front-passenger seat.
Adjust the height so that the upper part of the
seat belt is routed across the center of your
shoulder.
XTo raise: slide the belt sash guide upwards.
The belt sash guide engages in various
positions.XTo lower: press and hold belt sash guide
release :.XSlide the belt sash guide downwards.XRelease belt sash guide release : and
make sure that the belt sash guide has
engaged.
Releasing seat belts
XPress release button ?(Y page 53) and
guide belt tongue ; back towards belt
sash guide :.
!
Make sure that the seat belt is fully rolled
up. Otherwise, the seat belt or belt tongue
will be trapped in the door or in the seat
mechanism. This could damage the door,
the door trim panel and the seat belt.
Damaged seat belts can no longer fulfill
their protective function and must be
replaced. Consult an authorized Mercedes-
Benz Center.
Belt warning for the driver and front
passenger
Regardless of whether the driver and front
passenger have fastened their seat belts
already, the 7 seat belt warning lamp
lights up for 6 seconds after every engine
start. It then goes out if the driver and the
front passenger have fastened their seat
belts.
If the driver's seat belt is not fastened after
the engine is started, an additional warning
tone will sound. The warning tone goes out
after approximately six seconds or once the
driver's seat belt is fastened.
54Occupant safetySafety

section must never be exploited in a reckless
or dangerous manner which could jeopardize
the user's safety or the safety of others.
Always adjust your driving style to the
prevailing road and weather conditions and
keep a safe distance to other road users and
objects on the street.
If a driving system malfunctions, other driving
safety systems may also switch off. Observe
indicator and warning lamps that may come
on as well as messages in the multifunction
display that may appear.
i Please note that the driving safety
systems described only work as effectively
as possible when there is adequate contact
between the tires and the road surface. Pay
particular attention to the information
regarding tires, recommended minimum
tire tread depths etc. in the "Wheels and
tires" section ( Y page 322).
In wintry driving conditions, always use
winter tires (M+S tires) and if necessary,
snow chains. Only in this way will the
driving safety systems described in this
section work as effectively as possible.
ABS (Anti-lock Braking System)
Important safety notes
i Observe the "Important safety notes"
section ( Y page 64).
ABS regulates brake pressure in such a way
that the wheels do not lock when you brake.
This allows you to continue steering the
vehicle when braking.
ABS works from a speed of about
5 mph(8 km/h) upwards, regardless of road-
surface conditions. ABS works on slippery
surfaces, even when you only brake gently.
GWARNING
If the ABS malfunctions, other driving systems
such as the BAS or the ESP ®
are also switched
off. Observe indicator and warning lamps that
may come on as well as messages in the
multifunction display that may appear.
If the ABS malfunctions, the wheels may lock
during hard braking, reducing the steering
capability and extending the braking distance.
The ! warning lamp in the instrument
cluster lights up when the ignition is switched
on. It goes out when the engine is running.
Braking
If ABS intervenes when braking, you will feel
a pulsing in the brake pedal.
XIf ABS intervenes: continue to depress the
brake pedal with force until the braking
situation is over.XTo make a full brake application:
depress the brake pedal with full force.
The pulsating brake pedal can be an
indication of hazardous road conditions, and
functions as a reminder to take extra care
while driving.
GWARNING
Do not pump the brake pedal. Use firm, steady
brake pedal pressure instead. Pumping the
brake pedal defeats the purpose of the ABS
and significantly reduces braking
effectiveness.
BAS (Brake Assist System)
i Observe the "Important safety notes"
section ( Y page 64).
BAS operates in emergency braking
situations. If you depress the brake pedal
quickly, BAS automatically boosts the braking
force, thus shortening the stopping distance.
XKeep the brake pedal firmly depressed until
the emergency braking situation is over.
ABS prevents the wheels from locking.
The brakes will function as usual once you
release the brake pedal. BAS is deactivated.
Driving safety systems65SafetyZ

GWARNING
If the BAS malfunctions, the brake system still
functions, but without the additional brake
boost available that the BAS would normally
provide in an emergency braking maneuver.
Therefore, the braking distance may increase.
ESP ®
(Electronic Stability Program)
Important safety notes
i See the "Important safety notes" section
( Y page 64).
If ESP ®
detects that the vehicle is deviating
from the direction desired by the driver, one
or more wheels are braked to stabilize the
vehicle. If necessary, the engine output is also
modified to keep the vehicle on the desired
course within physical limits. ESP ®
assists
the driver when pulling away on wet or
slippery roads. ESP ®
can also stabilize the
vehicle during braking.
If ESP ®
intervenes, the ÷ ESP®
warning
lamp flashes in the instrument cluster.
GWARNING
Under no circumstances should you
deactivate ESP ®
when the ÷ ESP®
warning lamp in the instrument cluster
flashes. Proceed as follows:
R when driving off, apply as little throttle as
possible.
R while driving, ease up on the accelerator
pedal.
R adapt your speed to suit the prevailing road
and weather conditions.
Failure to observe these guidelines could
cause the vehicle to skid. ESP ®
cannot
prevent accidents resulting from excessive
speed.
! Only operate the vehicle for a maximum
of ten seconds on a brake test
dynamometer. Switch off the ignition.
Application of the brakes by ESP ®
may
otherwise destroy the brake system.
! Function or performance tests may only
be performed on a 2-axle dynamometer. If
you wish to operate the vehicle on such a
dynamometer, please consult an
authorized Mercedes-Benz Center
beforehand. You could otherwise damage
the drive train or the brake system.
i Only use wheels with the recommended
tire sizes. Only then will ESP ®
function
properly.
4ETS (Electronic Traction System)
i Observe the "Important safety notes"
section ( Y page 64).
Traction control is part of ESP ®
.
Traction control brakes the drive wheels
individually if they spin. This enables you to
pull away and accelerate on slippery surfaces,
for example if the road surface is slippery on
one side. In addition, more drive torque is
transferred to the wheel or wheels with
traction.
Traction control remains active if you
deactivate ESP ®
.
GWARNING
Traction control cannot reduce the risk of an
accident if you drive too fast. Traction control
cannot override the laws of physics.
Deactivating/activating ESP ®
i
Observe the "Important safety notes"
section ( Y page 64).
GWARNING
ESP ®
should not be deactivated during
normal driving other than in the
circumstances described below. Disabling
the system will reduce vehicle stability in
driving maneuvers.
Do not deactivate ESP ®
when the emergency
or spare wheel is mounted.
66Driving safety systemsSafety

ESP®
is activated automatically when the
engine is started.
It may be best to deactivate ESP ®
in the
following situations:
R when using snow chains
R in deep snow
R on sand or gravelGWARNING
Switch on ESP ®
immediately if one of the
previously stated conditions is no longer met.
Otherwise, ESP ®
cannot stabilize the vehicle
if it begins to lurch or when a wheel spins.
When you deactivate ESP ®
:
R ESP ®
no longer improves driving stability.
R the engine's torque is no longer limited and
the drive wheels can spin. The spinning of
the wheels results in a cutting action, which
provides better grip.
R traction control is still activated.
R ESP ®
still provides support when you
brake.
If ESP ®
is deactivated and one or more wheels
start to spin, the ÷ ESP®
warning lamp in
the instrument cluster flashes. In such
situations, ESP ®
will not stabilize the vehicle.
XTo deactivate: press button :.
The å ESP®
OFF warning lamp in the
instrument cluster lights up.GWARNING
When the å ESP®
OFF warning lamp is lit,
ESP ®
is deactivated.
If the ÷ ESP®
warning lamp and the
å ESP®
OFF warning lamp remain lit,
ESP ®
is not available due to a malfunction.
When ESP ®
is deactivated or not operational,
vehicle stability in standard driving
maneuvers is reduced.
Adapt your speed and driving to the prevailing
road conditions and to the non-operating
status of the ESP ®
.
! Avoid spinning the driven wheels for an
extended period with ESP ®
deactivated.
You could otherwise damage the drivetrain.
XTo activate: press button :.
The å ESP®
OFF warning lamp in the
instrument cluster goes out.
ESP ®
trailer stabilization
If your vehicle with trailer (vehicle/trailer
combination) begins to lurch, you can only
stabilize the vehicle/trailer combination by
depressing the brake firmly.
In this situation, ESP ®
assists you and can
detect if the vehicle/trailer combination
begins to lurch. ESP ®
slows the vehicle down
by braking and limiting the engine output until
the vehicle/trailer combination has
stabilized.
Trailer stabilization is active from a speed of
approximately 40 mph(65 km/h).
GWARNING
The system will not be able to assist when the
trailer jackknifes
R if the ESP ®
has switched off due to a
malfunction
R on wet or icy roads
R on roads with slippery surface
R in sand or gravel
Driving safety systems67SafetyZ