ignition MERCEDES-BENZ S-Class 2012 W221 Repair Manual

or yellow. Always secure the vehicle against
rolling away before leaving it.
! Always switch the ignition off and take the
key with you when leaving the vehicle.
Automatic engine switch-off
The ECO start/stop function switches the
engine off automatically if the vehicle is
braked to a standstill and the brake remains
depressed with the transmission in position
D or N.
i You can still activate the HOLD function
when the vehicle is stationary, even if the
engine has been switched off
automatically. It is then not necessary to
continue applying the brakes during the
automatic stop phase. When you depress
the accelerator pedal, the engine starts
automatically and the braking effect of the
HOLD function is deactivated. Depress the
accelerator pedal carefully, as the engine
must be started first.
The engine is only switched off if:
R the outside temperature is within the range
which is suitable for the system.
R the engine is at normal operating
temperature.
R the set temperature for the vehicle interior
has been reached.
R the battery is sufficiently charged.
R the system detects that the windshield is
not fogged up when the air-conditioning
system is switched on.
R the hood is closed.
R no engine-relevant diagnostics are active.
R the driver's door is closed and the seat belt
is fastened.
Automatic engine start
The engine is started automatically if you:
R release the brake pedal when HOLD is not
activated and the transmission is in
position D or N
R shift the transmission to position R
R depress the accelerator pedal
R switch off the ECO start/stop function or
switch to drive program S or M
R unfasten your seat belt or open the driver's
door
The engine is also started automatically if:
R the vehicle starts to roll.
R the brake system requires this.
R the system detects moisture on the
windshield when the air-conditioning
system is switched on.
R the temperature in the vehicle interior
deviates from the set range.
R the charge level of the battery is too low.
Deactivating/activating the ECO start/
stop function
General information
You can deactivate and activate the ECO
start/stop function using COMAND
( Y page 261).
i You can also use the programmable
button ( Y page 120) to activate and
deactivate the ECO start/stop function if
you have assigned this function to the
button.
Deactivating
XDeactivate the ECO start/stop function
using COMAND ( Y page 261):
The ¤ ECO symbol goes out and the
Stop/Start deactivated display
message is shown in the multifunction
display.
i If drive program S or M has been selected,
the ECO start/stop function is always
deactivated.
Driving307Driving and parkingZ

Problems with the engineProblemPossible causes/consequences and M SolutionsThe engine does not
start. The starter motor
can be heard.R There is a malfunction in the engine electronics.
R There is a malfunction in the fuel supply.XBefore attempting to start the engine again, turn the SmartKey
in the ignition back to position 0 or press the Start/Stop button
repeatedly until all indicator lamps in the instrument cluster go
out.XTry to start the engine again ( Y page 304). Avoid excessively
long and frequent attempts to start the engine as these will drain
the battery.
If the engine does not start after several attempts:
XConsult a qualified specialist workshop, e.g. an authorized
Mercedes-Benz Center.The engine does not
start. You cannot hear
the starter motor.The on-board voltage is too low because the battery is too weak
or discharged.XJump-start the vehicle ( Y page 481).
If the engine does not start despite attempts to jump-start it:
XConsult a qualified specialist workshop, e.g. an authorized
Mercedes-Benz Center.The starter motor was exposed to a thermal load that was too high.XAllow the starter motor to cool down for approximately two
minutes.XTry to start the engine again.
If the engine still does not start:
XConsult a qualified specialist workshop, e.g. an authorized
Mercedes-Benz Center.Driving309Driving and parkingZ

NNeutralDDrive
iThe 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 312) in the multifunction display.
Engaging park position P
XPush the DIRECT SELECT lever in the
direction of arrow P.
i
The automatic transmission shifts
automatically into park position P if you
open the driver's door when the vehicle is
stationary or driving at very low speed, and
the transmission is in position D or R.
! If the engine speed is too high or the
vehicle is moving, do not shift the
automatic transmission directly from D to
R , from R to D or directly to P. The
automatic transmission could otherwise be
damaged.
Engaging reverse gear R
! Only shift the automatic transmission to
R when the vehicle is stationary.
i The ECO start/stop function is not
available when reverse gear is engaged.
For further information on the ECO start/
stop function, see ( Y page 306).
XWhen the vehicle is stationary, depress the
brake pedal.XPush the DIRECT SELECT lever up past the
first point of resistance.
Neutral N with ECO start/stop function
activated
The ECO start/stop function switches the
engine off automatically if the vehicle is
braked to a standstill when in neutral N and
the brake is still depressed.
For further information on the ECO start/stop
function ( Y page 306).
Shifting to neutral NXWhen the vehicle is stationary, depress the
brake pedal.XPush the DIRECT SELECT lever up or down
to the first point of resistance.
If the engine has been switched off, the
automatic transmission automatically
switches to N.
Remaining in neutral N
If the automatic transmission is to remain in
neutral N, e.g. for washing the vehicle in car
washes with a towing device, please observe
the following instructions:
GWARNING
When leaving the SmartKey in the starter
switch, do not leave children unattended in
the vehicle. It is possible for children to switch
on the ignition which could result in
unsupervised use of vehicle equipment.
Unsupervised use of vehicle equipment could
result in an accident and/or serious personal
injury.
Using the SmartKey:
R make sure that the ignition is switched on.
R when the vehicle is stationary, depress the
brake pedal and keep it depressed.
R shift to neutral N.
R release the brake pedal.
R if applied, release the electric parking
brake.
R switch off the ignition and leave the
SmartKey in the ignition lock.
Using KEYLESS-GO:
R make sure that the ignition is switched on.
R when the vehicle is stationary, depress the
brake pedal and keep it depressed.
R engage park position P.
R release the brake pedal.
Automatic transmission311Driving and parkingZ

Rremove the Start/Stop button from the
ignition lock.
R insert the SmartKey into the ignition lock.
R switch on the ignition.
R depress the brake pedal and keep it
depressed.
R shift to neutral N.
R release the brake pedal.
R if applied, release the electric parking
brake.
R switch off the ignition and leave the
SmartKey in the ignition lock.
Transmission position D with ECO
start/stop function activated
The ECO start/stop function switches the
engine off automatically if the vehicle is
braked to a standstill when in transmission
position D and the brake is still depressed.
For further information on the ECO start/stop
function ( Y page 306).
Shifting to transmission position D
XWhen the vehicle is stationary, depress the
brake pedal.XPush the DIRECT SELECT lever down past
the first point of resistance.
Transmission position display
The current transmission position is shown in
the multifunction display.
:Transmission positioni The arrows in the transmission position
display show how and into which
transmission positions you can change
using the DIRECT SELECT lever.
! If the transmission position display in the
multifunction display is not working, you
should pull away carefully to check whether
the desired transmission position is
engaged. Ideally, you should select
transmission position D and drive program
E (drive program C on AMG vehicles) or S.
Do not restrict the shift range.
Transmission positions
BPark position
Do not shift the transmission into
position P unless the vehicle is
stationary. The parking lock should
not be used as a brake when
parking. In addition to engaging the
parking lock, you must always
apply the electric parking brake to
secure the vehicle.
If the vehicle electronics are
malfunctioning, the transmission
may be locked in position P.
Have the vehicle electronics
checked at a qualified specialist
workshop, e.g. an authorized
Mercedes-Benz Center,
immediately.CReverse gear
Only shift the transmission to R
when the vehicle is stationary.312Automatic transmissionDriving and parking

Problems with the transmissionProblemPossible causes/consequences and M SolutionsThe transmission has
problems shifting gear.The transmission is losing oil.XHave the transmission checked at a qualified specialist
workshop, e.g. an authorized Mercedes-Benz Center,
immediately.The acceleration ability
is deteriorating.
The transmission no
longer changes gear.The transmission is in emergency mode.
It is only possible to shift into second gear and reverse gear.XStop the vehicle.XShift the transmission to position P.XSwitch off the engine.XWait at least 10 seconds before restarting the engine.XShift the transmission to position D or R.
If D is selected, the transmission shifts into second gear; if R is
selected, the transmission shifts into reverse gear.XHave the transmission checked at a qualified specialist
workshop, e.g. an authorized Mercedes-Benz Center,
immediately.Transfer case
This section is only valid for vehicles with 4-
wheel drive (4MATIC). Power is always
transmitted to both axles.
! Performance tests may only be carried
out on a 2-axle dynamometer. The brake
system or transfer case could otherwise be
damaged. Contact a qualified specialist
workshop for a performance test.
Mercedes-Benz recommends that you use
an authorized Mercedes-Benz Center for
this purpose.
! To prevent ESP ®
from intervening, the
ignition must be switched off (SmartKey or
the Start/Stop button in position 0 or 1) if:
R the electric parking brake is being tested
on a brake dynamometer.
R the vehicle is being towed with only one
axle raised (not permitted for vehicles
with 4MATIC).The brake system could otherwise be
damaged.
Refueling
Important safety notes
GWARNING
Gasoline and diesel fuels are highly flammable
and poisonous. They burn violently and can
cause serious injury.
Never allow sparks, flames or smoking
materials near gasoline or diesel fuel!
Turn off the engine before refueling.
Whenever you are around gasoline or diesel
fuel, avoid inhaling fumes and any skin or
clothing contact. Extinguish all smoking
materials.
Direct skin contact with fuels and the
inhalation of fuel vapors are damaging your
health.
Refueling317Driving and parkingZ

GWARNING
Overfilling of the fuel tank may create
pressure in the system which could cause a
gas discharge. This could cause the gasoline
to spray back out when removing the fuel
pump nozzle, which could cause personal
injury.
GWARNING
Hybrid vehicles: be sure to read the "HYBRID"
supplement. Otherwise, you could fail to
recognize dangers.
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).
You will usually find information about the
fuel grade on the pump. If you cannot find
the label on the pump, ask the staff for
assistance.
You can find more information under "Fuel"
( Y page 525), 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 525), or by contacting an
authorized Mercedes-Benz Service Center
or visiting http://www.mbusa.com (USA
only).
318RefuelingDriving and parking

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
obtained from oil companies, e.g. at gas
stations.
Refueling
Fuel filler flap
The fuel filler flap is unlocked or locked
automatically when you open or close the
vehicle with the SmartKey or using KEYLESS-
GO.
The position of the fuel filler cap is displayed
in the instrument cluster 8. The arrow
next to the filling pump indicates the side of
the vehicle.
:To open the fuel filler flap;To insert the fuel filler cap=Tire pressure table?Fuel type
Opening
XSwitch off the engine.XRemove the SmartKey from the ignition
lock.KEYLESS-GO: open the driver’s door. This
switches the ignition to position 0, which
corresponds to having removed the
SmartKey. The driver’s door can be closed
again.XPress the fuel filler flap in the direction of
arrow :.
The fuel filler flap opens slightly.XOpen the fuel filler flap.XTurn the fuel filler cap counter-clockwise
and remove it.XInsert the fuel filler cap into the holder
bracket on the inside of filler flap ;.XCompletely insert the pump nozzle into the
filler neck and refuel.XOnly fill the tank until the pump nozzle
switches off.
! Overfilling the fuel tank could damage the
fuel system.
Closing
XReplace the fuel filler cap and turn it
clockwise. The fuel filler cap audibly
engages.XClose the fuel filler flap.
i If you drive with the fuel filler cap open,
the reserve fuel warning lamp flashes. In
addition, the ; Check Engine warning
lamp may light up. A message appears in
the multifunction display ( Y page 407).
For further information on warning and
indicator lamps in the instrument cluster,
see ( Y page 427).
i Close the fuel filler flap before locking the
vehicle. A locking pin otherwise prevents
the fuel filler flap from closing after the
vehicle has been locked.
Refueling319Driving and parkingZ

Problems with fuel and the fuel tankProblemPossible causes/consequences and M SolutionsFuel is leaking from the
vehicle.GRisk of explosion or fire
The fuel line or the fuel tank is defective.
XTurn the SmartKey to position 0(Y page 303) in the ignition lock
immediately and remove it.XDo not restart the engine under any circumstances.XConsult a qualified specialist workshop.The fuel filler flap
cannot be opened.The fuel filler flap is not unlocked.
or
The SmartKey battery is discharged.XUnlock the vehicle ( Y page 78).
or
XUnlock the vehicle using the mechanical key ( Y page 81).The fuel filler flap is unlocked, but the opening mechanism is
jammed.XConsult a qualified specialist workshop.The engine will not
start.The fuel tank of a vehicle with a diesel engine has been run
completely dry.XRefuel the vehicle with at least 5.3 US qt (5 liters) of diesel.XTurn the ignition on for at least 10 seconds ( Y page 303).XStart the engine continuously for up to 10 seconds until it runs
smoothly.
orXStart the engine via the touch-start function. To do this, turn the
SmartKey to position 3 (Y page 303) in the ignition lock and
then release it immediately.
If the engine does not start:
XTurn the ignition on again for approximately 10 seconds
( Y page 303).XStart the engine again continuously for up to 10 seconds until
it runs smoothly.
orXStart the engine again via the touch-start function.
If the engine does not start after three attempts:
XConsult a qualified specialist workshop.320RefuelingDriving and parking

use a sponge and cold water to clean it. DEF
residues crystallize after time and
contaminate the affected surfaces.
! DEF is not a fuel additive and must not be
added to the fuel tank. If DEF is added to
the fuel tank, this can lead to engine
damage.
i If you are adding between maintenance
intervals, add approximately 1 gallon (3.8 l)
of DEF to the DEF tank. One gallon (3.8 l)
of DEF is approximately 2 DEF refill bottles.
Then, have the DEF supply checked and
filled completely if necessary. For this
purpose, Mercedes-Benz recommends a
qualified specialist workshop.
Further information on DEF ( Y page 527).
The filler neck for DEF is located under the
"Minispare" emergency spare wheel in the
trunk floor.XSwitch off the ignition.XOpen the trunk.XLift up the trunk floor ( Y page 436).XTurn the "Minispare" emergency spare
wheel fastening in the direction of the
arrow and remove it.XRemove the "Minispare" emergency spare
wheel.XTurn DEF cap : counter-clockwise and
remove it.XTurn DEF filler cap ; counter-clockwise
and open it.
Filler cap ; is secured with a plastic strap.XUnscrew the covering cap from DEF refill
bottle =.XPlace DEF refill bottle = on the filler neck
as shown and screw on clockwise hand-
tight.
! Only screw on the DEF refill bottle hand-
tight. It could otherwise be damaged.
322RefuelingDriving and parking

XPress DEF refill bottle = down.
The DEF tank is filled. This may take up to
one minute.
i If the DEF refill bottle is no longer pressed
down, the filling process stops and the
partially emptied bottle can be removed.
XRelease DEF refill bottle =.XTurn DEF refill bottle = counter-clockwise
and remove it.XPlace DEF filler cap ; on the filler neck and
turn it clockwise.XInsert DEF cap : as shown and turn it
clockwise as far as it will go.XPlace the "Minispare" emergency spare
wheel in the emergency spare wheel well
above the DEF tank.XInsert the "Minispare" emergency spare
wheel fastening and tighten clockwise.XFold the trunk floor down.XClose the trunk lid.XDrive at a speed above 10 mph (16 km/h).
The Check Additive See Operator's
Manual message goes out after
approximately one minute.
i If the Check Additive See
Operator's Manual message remains
shown in the multifunction display, add an
additional bottle of DEF.
i Then, have the DEF supply checked at a
qualified specialist workshop and
completely refilled if necessary.
Parking
Important safety notes
GWARNING
Do not park this vehicle in areas where
combustible materials can come into contact
with the hot exhaust system. Combustible
materials, such as grass, hay or leaves could
be ignited by the hot exhaust system and
cause a vehicle fire. Do not park the vehicle
on dry grassland or harvested grain fields.
Unintended vehicle movement can cause
serious personal injury or damage to the
vehicle or the vehicle drivetrain. To reduce
such risks, always do the following before
turning off the engine and leaving the vehicle:
R keep your right foot on the brake pedal.
R engage the electric parking brake.
R shift the automatic transmission into park
position P.
R slowly release the brake pedal.
R when parked on an incline, always turn the
front wheels towards the road curb.
R turn the SmartKey in the ignition lock to
position 0 and remove the SmartKey from
the ignition lock, or press the KEYLESS-GO
Start/Stop button.
R take the SmartKey with you and lock the
vehicle when leaving.
Switching off the engine
Important safety notes
GWARNING
Do not turn off the engine before the vehicle
has come to a complete stop. With the engine
not running, there is no power assistance for
the brake and steering systems. In this case,
it is important to keep in mind that a
considerably higher degree of effort is
necessary to brake and steer the vehicle.
Parking323Driving and parkingZ