catalytic converter MERCEDES-BENZ R-Class 2012 W251 Owner's Manual

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

Start/Stop button
=USA only?Canada onlyXPosition 0: if Start/Stop button : has not
yet been pressed, this corresponds to the
SmartKey being removed from the ignition.XPosition 1: press Start/Stop button :.
You can now activate the windshield
wipers, for example.
i If you then open the driver's door when in
this position, the power supply is
deactivated.
XPosition 2 (ignition): press Start/Stop
button : twice.
i
If you press Start/Stop button : once
when in this position and the driver's door
is open, the power supply is deactivated
again.
As soon as the ignition is switched on, all the
indicator lamps in the instrument cluster light
up. If an indicator lamp does not go out after
the engine is started or if it lights up while the
vehicle is in motion, see ( Y page 239).
Starting the engine
Important safety notes
GWARNING
Inhalation of exhaust gas is hazardous to your
health. All exhaust gas contains carbon
monoxide (CO), and inhaling it can cause
unconsciousness and possible death.
Do not run the engine in confined areas (such
as a garage) which are not properly ventilated.
If you think that exhaust gas fumes are
entering the vehicle while driving, have the
cause determined and corrected
immediately. If you must drive under these
conditions, drive only with at least one
window fully open at all times.
! Do not depress the accelerator pedal
when starting the engine.
i Vehicles with a gasoline engine: the
catalytic converter is preheated for up to
30 seconds after a cold start. During this
time, the engine sound may be different.
Automatic transmissionXShift the transmission to position P.
The transmission position display in the
multifunction display shows P.
i
You can also start the engine when the
transmission is in position N.
Starting procedure with the SmartKey
i To start the engine using the SmartKey
instead of KEYLESS-GO, pull the Start/
Stop button out of the ignition lock.
XTo start a gasoline engine: turn the
SmartKey to position 3 in the ignition lock
( Y page 145) and release it as soon as the
engine is running.XTo start a diesel engine: turn the
SmartKey to position 2 in the ignition lock
( Y page 145).
The % preglow indicator lamp in the
instrument cluster lights up.XWhen the % preglow indicator lamp
goes out, turn the SmartKey to position 3
( Y page 145) and release it as soon as the
engine is running.
i You can start the engine without preglow
if the engine is warm.
146DrivingDriving and parking

Using KEYLESS-GO to start the engineGWARNING
As long as the SmartKey is in your vehicle, the
vehicle can be started. Therefore, never leave
children unattended in the vehicle, as they
could otherwise accidentally start the engine.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Do
not leave children unattended in the vehicle,
or with access to an unlocked vehicle. A
child's unsupervised access to a vehicle could
result in an accident and/or serious personal
injury.
i The Start/Stop button can be used to
start the vehicle without inserting the
SmartKey into the ignition lock. The Start/
Stop button must be inserted into the
ignition lock and the SmartKey must be in
the vehicle.
XDepress the brake pedal and keep it
depressed.XTo start a gasoline engine: press the
Start/Stop button ( Y page 145) once.
The engine starts.XTo start a diesel engine: press the Start/
Stop button ( Y page 145) once.
Preglow is activated and the engine starts.
i If the engine is warm, the preglow time is
shortened.
Pulling away
Automatic transmission
GWARNING
It is dangerous to shift the automatic
transmission out of parking position P or
neutral position N if the engine speed is
higher than idle speed. If your foot is not firmly
on the brake pedal, the vehicle could
accelerate quickly forward or in reverse. You
could lose control of the vehicle and hit
someone or something. Only shift into gear
when the engine is idling normally and when
your right foot is firmly on the brake pedal.
i It is only possible to shift the transmission
from position P to the desired position if
you depress the brake pedal. Only then is
the parking lock released. If you do not
depress the brake pedal, you can move the
DIRECT SELECT lever but the parking lock
remains engaged.XDepress the brake pedal and keep it
depressed.XShift the transmission to position D or R.XRelease the parking brake ( Y page 164).XRelease the brake pedal.XCarefully depress the accelerator pedal.
!
If a warning tone sounds and the
Release Park. Brake message appears
in the multifunction display, the parking
brake is still applied. Release the parking
brake.
i The vehicle locks centrally once you have
pulled away. The locking knobs in the doors
drop down.
You can open the doors from the inside at
any time.
You can also deactivate the automatic
locking feature ( Y page 208).
i Upshifts take place at higher engine
speeds after a cold start. This helps the
catalytic converter to reach its operating
temperature more quickly.
Hill start assist
Hill start assist helps you when pulling away
forwards or in reverse on an uphill gradient.
It holds the vehicle for a short time after you
have removed your foot from the brake pedal.
This gives you enough time to move your foot
from the brake pedal to the accelerator pedal
and depress it before the vehicle begins to
roll.
Driving147Driving and parkingZ

ProblemPossible causes/consequences and M SolutionsVehicles with a
gasoline engine:
The engine is not
running smoothly and
is misfiring.There is a malfunction in the engine electronics or a mechanical
component of the engine management system.XOnly depress the accelerator pedal slightly.XHave the cause rectified immediately at a qualified specialist
workshop, e.g. an authorized Mercedes-Benz Center.
Otherwise, non-combusted fuel may get into the catalytic
converter and damage it.The coolant
temperature gauge
shows a value above
248 ‡ (120 †).The coolant level is too low. The coolant is too hot and the engine
is no longer being cooled sufficiently.XStop as soon as possible and allow the engine and the coolant
to cool down.XCheck the coolant level ( Y page 285). Observe the warning
notes as you do so and add coolant if necessary.Automatic transmission
Important safety notes
GWARNING
It is dangerous to shift the automatic
transmission out of parking position P or
neutral position N if the engine speed is
higher than idle speed. If your foot is not firmly
on the brake pedal, the vehicle could
accelerate quickly forward or in reverse. You
could lose control of the vehicle and hit
someone or something. Only shift into gear
when the engine is idling normally and when
your right foot is firmly on the brake pedal.
GWARNING
Keep in mind that turning off the engine alone
only will shift the automatic transmission into
neutral position N automatically.
Always shift the automatic transmission into
park position P before turning off the engine.
Otherwise the vehicle could roll away which
could result in an accident and/or serious
personal injury.
DIRECT SELECT lever
Overview of transmission positions
The DIRECT SELECT lever is on the right of the
steering column.
PPark position with parking lockRReverse gearNNeutralDDrive
i The DIRECT SELECT lever always returns
to its original position. The current
transmission position P, R , N or D appears
in the transmission position display
( Y page 151) in the multifunction display.
150Automatic transmissionDriving and parking

to spray back out when removing the fuel
pump nozzle, which could cause personal
injury.GWARNING
Do not fill diesel tanks with gasoline. Do not
mix diesel fuel with gasoline. Otherwise the
fuel system and engine could be damaged. In
addition, the vehicle could catch fire.
! Do not use gasoline to refuel vehicles with
a diesel engine. Do not use diesel to refuel
vehicles with a gasoline engine. Even a
small quantity of the wrong fuel will
damage the fuel system and engine.
! Do not switch on the ignition if you
accidentally refuel with the wrong fuel.
Otherwise, the fuel will enter the fuel lines.
Notify a qualified specialist workshop and
have the fuel tank and fuel lines drained
completely.
Gasoline
Fuel grade
! You should only refuel with unleaded
premium-grade gasoline as this avoids
damaging the catalytic converter.
If engine running problems are apparent,
have the cause checked immediately and
repaired. Excess unburned fuel can
otherwise enter the catalytic converter,
leading to overheating and possibly
causing a fire.
! Use a filter when refueling from a fuel can.
Otherwise, the fuel lines and/or injection
system could be blocked by particles from
the fuel can.
i Only refuel with premium-grade unleaded
gasoline with a specified minimum octane
number of 91 (average value of 96 RON/
86 MON).
Usually, you will find information about the
fuel grade on the pump. If you cannot find
the label on the gasoline pump, ask the gas
station staff.
You can find more information under “Fuel”
( Y page 356), or by contacting an
authorized Mercedes-Benz Service Center
or visiting http://www.mbusa.com (USA
only).
Diesel
Fuel grade
! Only refuel with ULTRA-LOW SULFUR
DIESEL FUEL (ULSD, 15 ppm SULFUR
MAXIMUM). Using other diesel fuels could
result in increased wear and damage to the
engine and/or exhaust system.
Never refuel with marine diesel or heating
oil.
Do not mix these fuels with diesel fuels and
do not use any special additives, as this
may result in damage.
! Use a filter when adding fuel from a fuel
can. Otherwise, the fuel lines and/or the
fuel injection system could be blocked by
particles from the fuel can.
i Usually, you will find information about
the fuel grade on the pump. If you cannot
find the label on the gasoline pump, ask the
gas station staff.
You can find more information under “Fuel”
( Y page 356), or by contacting an
authorized Mercedes-Benz Service Center
or visiting http://www.mbusa.com (USA
only).
Low outside temperatures
! Do not use gasoline to refuel vehicles with
a diesel engine. Never mix diesel with
gasoline or kerosene, as this may result in
damage to the engine or fuel system.
Diesel fuel with improved cold flow properties
is available during the winter months. Further
information on fuel properties can be
Refueling157Driving and parkingZ

damage to the engine or the catalytic
converter. Have excess oil siphoned off.
For further information on engine oil, see
( Y page 358).XReplace cap : on the filler neck and
tighten clockwise.
Ensure that the cap locks into place
securely.
Checking and adding other service
products
Checking the coolant level
Only check the coolant level when the vehicle
is on a level surface and the engine has cooled
down.
XTurn the SmartKey to position
2 (Y page 145) in the ignition lock.
On vehicles with KEYLESS-GO, press the
Start/Stop button twice ( Y page 145).XCheck the coolant temperature gauge in
the multifunction display.
The coolant temperature must be below
158 ‡ (70 †).GWARNING
In order to avoid any potentially serious burns:
R use extreme caution when opening the
hood if there are any signs of steam or
coolant leaking from the cooling system, or
if the coolant temperature display indicates
that the coolant is overheated.
R do not remove the pressure cap on the
coolant reservoir if the coolant temperature
is above 158 ‡ (70 †). Allow the engine to
cool down before removing the cap. The
coolant reservoir contains hot fluid and is
under pressure.
R using a rag, slowly turn the cap
approximately 1
/ 2 turn to relieve excess
pressure. If opened immediately, scalding
hot fluid and steam will be blown out under
pressure.
R do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts.XSlowly turn cap : half a turn counter-
clockwise and allow excess pressure to
escape.XTurn cap : further counter-clockwise and
remove it.
If the coolant is at the level of marker bar
= in the filler neck when cold, there is
enough coolant in coolant expansion
tank ;.
If the coolant is approximately 0.6 in
(1.5 cm) above marker bar = in the filler
neck when warm, there is enough coolant
in coolant expansion tank ;.XIf necessary, add coolant that has been
tested and approved by Mercedes-Benz.XReplace cap : and turn it clockwise as far
as it will go.
For further information on coolant, see
( Y page 359).
Windshield washer system and
headlamp cleaning system
The washer fluid reservoir is used for both the
windshield washer system and the headlamp
cleaning system.
i Vehicle components and their service
products must match. You should,
Engine compartment285Maintenance and careZ

Jump-startingGWARNING
Failure to follow these directions will cause damage to the electronic components, and can lead
to a battery explosion and severe injury or death.
Never lean over batteries while connecting or jump starting. You might get injured.
Battery fluid contains sulfuric acid. Do not allow this fluid to come in contact with eyes, skin or
clothing. In case it does, immediately flush affected area with water, and seek medical help if
necessary.
A battery will also produce hydrogen gas, which is flammable and explosive. Keep flames or
sparks away from battery, avoid improper connection of jumper cables, smoking, etc.
Attempting to jump start a frozen battery can result in it exploding, causing personal injury.
Read all instructions before proceeding.
! Avoid repeated and lengthy starting attempts. Otherwise, non-combusted fuel may
damage the catalytic converter 36
and create a risk of fire.
Do not use a rapid-charging device to start the engine.
Make sure the jumper cables are not damaged.
Make sure the jumper cables are not touching any other metal objects when they are
connected to the battery.
If your vehicle's battery is discharged, the engine can be jump-started from another vehicle
or from a second battery using jumper cables.
Observe the following points:
XThe battery is not accessible in all vehicles. If the other vehicle's battery is not accessible,
jump-start the vehicle using a second battery or a jump-starting device.XOnly jump-start the vehicle when the engine is cold and the catalytic converter system has
cooled down 37
.XDo not start the engine if the battery is frozen. Let the battery thaw first.XJump-starting may only be performed from batteries with a nominal voltage of 12 V.XOnly use jumper cables which have a sufficient cross-section and insulated terminal clamps.XMake sure that the jumper cables cannot come into contact with parts, such as the pulley
or the fan. These parts move when the engine is started and while it is running.XIf the battery is fully discharged, leave the battery that is being used to jump-start connected
for a few minutes before attempting to start. This charges the empty battery a little.
i Jumper cables and further information about jump-starting can be obtained from any
authorized Mercedes-Benz Center, for example.
XMake sure that the two vehicles do not touch.XApply the parking brake firmly.XShift the transmission to position P.36
Only vehicles with a gasoline engine.
37 Only vehicles with a gasoline engine.Jump-starting313Breakdown assistanceZ

High outside temperatures
If DEF heats up over 122 ‡ (50 † ) for longer
periods, e.g. as a result of direct sunlight on
the DEF reservoir, DEF can decompose.
Ammonia vapors develop as a result.
GWARNING
When opening the filler cap of the DEF tank
ammonia gas vapors may escape. Refill DEF
in a well ventilated area only. Ammonia gas
vapors have a pungent odor and are
particularly irritating for your skin, mucous
membranes, and eyes. Inhaling ammonia gas
vapors will cause burning eyes, nose, and
throat, as well as coughing and watering eyes.
Low outside temperatures
DEF freezes at a temperature of
approximately 12 ‡ (–11 † ). The vehicle is
equipped with a DEF preheating system when
it leaves the factory. Winter operation is
therefore also guaranteed at temperatures
below 12 ‡(–11 † ).
Additives
! Only use DEF in accordance with ISO
22241. Do not use additives with DEF and
do not dilute DEF with water. This may
destroy the BlueTEC exhaust gas
aftertreatment system.
Damage resulting from the use of additives
or water is not covered by the Mercedes-
Benz Limited Warranty.
Purity
Assuring the purity of DEF is particularly
important with respect to avoiding
malfunctions in the exhaust gas
aftertreatment system.
If DEF is pumped out of the DEF tank, e.g.
during repair work, it must not be returned to
the tank. The purity of the fluid can no longer
be guaranteed.
! Impurities in DEF, e.g. due to other
service products, cleaning agents or dust,
lead to increased emission values, system
malfunctions, catalytic converter damage
or damage to the BlueTEC system.
Engine oil
Please bear the following in mind
The engine oils are matched to the
performance of Mercedes-Benz engines and
service intervals. You should therefore only
use engine oils and oil filters that are
approved for vehicles with maintenance
systems.
For a list of approved engine oils and oil filters,
consult an authorized Mercedes-Benz Center
or go to the Internet site
http://www.mbusa.com (USA only).
! Never use engine oil or an oil filter of a
specification other than is necessary to
fulfill the prescribed service intervals. Do
not change the engine oil or oil filter in
order to achieve longer replacement
intervals than those prescribed. You could
otherwise cause engine damage or damage
to the exhaust gas aftertreatment.
Follow the instructions in the service
interval display regarding the oil change.
Otherwise, you may damage the engine and
the exhaust gas aftertreatment.
The table shows which engine oils have been
approved for your vehicle.
ModelEngine
modelMB
ApprovalR 350 BlueTEC642229.51R 350276229.5
i MB Approval is indicated on the oil
containers.
Additives
! Do not use any additives in the engine oil.
This could damage the engine.
358Service products and capacitiesTechnical data