ignition MERCEDES-BENZ S-CLASS SEDAN 2012 Repair Manual

General information
iVehicles with a gasoline engine: the
engine runs at a higher engine speed during
a cold start so that the catalytic converter
can reach operating temperature more
quickly. The sound of the engine may
change during this time.
Automatic transmission
XShift 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 307) 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 307).
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 307) and release it as soon as the
engine is running.
i You can start the engine without preglow
if the engine is warm.
Using KEYLESS-GO to start the engine
GWARNING
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 manually 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. This mode for starting the
engine operates independently of the ECO
start/stop automatic engine start function.XDepress the brake pedal and keep it
depressed.XTo start a gasoline engine: press the
Start/Stop button ( Y page 307) once.
The engine starts.XTo start a diesel engine: press the Start/
Stop button ( Y page 307) 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
Driving309Driving and parkingZ

GWARNING
If the engine is switched off and the ECO
symbol is shown in green in the multifunction
display, the engine has been switched off
automatically. All of the vehicle's systems
remain active. If you open the door, unfasten
your seat belt or remove your foot from the
brake pedal, the engine will automatically
start. The vehicle may begin moving. You
could suffer serious or even fatal injury or
cause an accident resulting in injury or death.
Never leave the vehicle while the ECO symbol
in the multifunction display is shown in green
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
If the vehicle is braked to a standstill and the
brake remains depressed with the
transmission in position D or N, the ECO
start/stop function switches the engine off
automatically.
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.
Rthe 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 265).
i You can also use the programmable
button ( Y page 124) to activate and
deactivate the ECO start/stop function if
you have assigned this function to the
button.
Driving311Driving 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 308). 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.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 483).
If the engine does not start despite attempts to jump-start it:
XConsult a qualified specialist workshop.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.Vehicles with a
gasoline engine:
The engine is not
running smoothly and
is misfiring.There is a malfunction in the engine electronics or in a mechanical
component of the engine management system.XOnly depress the accelerator pedal slightly.XHave the cause rectified immediately at a qualified specialist
workshop.
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 463). Observe the warning
notes as you do so and add coolant if necessary.Driving313Driving and parkingZ

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 310).
Shifting to neutral N
XWhen 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.
Rif the electric parking brake is applied,
release it.
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.
R remove 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 the electric parking brake is applied,
release it.
R switch off the ignition and leave the
SmartKey in the ignition lock.
Drive 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 310).
Engaging drive 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.
Automatic transmission315Driving and parkingZ

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 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 10seconds 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 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.
! 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.
! Vehicles with 4MATIC must not be towed
with either the front or the rear axle raised,
as doing so will damage the transmission.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.
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
Refueling321Driving and parkingZ

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.
! Overfilling the fuel tank could damage the
fuel system.
! Take care not to spill any fuel on painted
surfaces. You could otherwise damage the
paintwork.
! 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.
Further information on fuel and on fuel grades
can be found in the "Fuel" section
( Y page 525).
Refueling
Fuel filler flap:To open the fuel filler flap;To insert the fuel filler cap=Tire pressure table?Fuel type
The fuel filler flap is unlocked or locked
automatically when you open or close the
vehicle with the SmartKey or with KEYLESS-
GO.
The position of the fuel filler cap 8 is
displayed in the instrument cluster. The arrow
next to the filling pump indicates the side of
the vehicle.
Opening
XSwitch off the engine.XRemove the SmartKey from the ignition
lock.XKEYLESS-GO: open the driver’s door.
This corresponds to SmartKey position 0:
"SmartKey removed".
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 fully.XTurn the fuel filler flap counter-clockwise
and remove it.XInsert the fuel filler cap into the holder
bracket on the inside of filler flap ;.322RefuelingDriving and parking

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 in the ignition lock immediately
and remove it ( Y page 307).XDo not restart the engine under any circumstances.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 about 10 seconds( Y page 307).XStart the engine continuously for up to 10 seconds until it runs
smoothly.
or
If the engine does not start:
XTurn the ignition on again for approximately
10 seconds( Y page 307).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.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 82).
or
XUnlock the vehicle using the mechanical key ( Y page 84).The fuel filler flap is unlocked, but the opening mechanism is
jammed.XConsult a qualified specialist workshop.324RefuelingDriving and parking

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.
! Only screw on the DEF refill bottle hand-
tight. It could otherwise be damaged.
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 the trunk floor up ( Y page 438).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.XPress DEF refill bottle = down.
The DEF tank is filled. This may take up to
one minute.
i To add between service intervals, fill the
DEF tank with approximately 1 gal (3.8 l) of
DEF. 1 gal (3.8 l) of DEF is equivalent to
approximately 2 DEF refill bottles. Then
have the DEF supply checked at a qualified
specialist workshop and completely refilled
if necessary.
XRelease DEF refill bottle =.
Refilling stops when the DEF refill bottle is
no longer pressed down. The DEF refill
bottle can be removed when it has been
only partially emptied.326RefuelingDriving and parking

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 faster than 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.
Further information on DEF ( Y page 527).
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.
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.
Parking327Driving and parkingZ

iIf you cannot turn off the engine as
described here, see "Engine emergency
stop" ( Y page 490).
Vehicles with automatic transmissionXApply the electric parking brake.XShift the transmission to position P.
Using the SmartKey
XTurn the SmartKey to position 0 in the
ignition lock and remove it.
The immobilizer is activated.
i If you turn off the engine with the
SmartKey and then remove it from the
ignition lock or open a front door, the
automatic transmission shifts to P
automatically.
Using KEYLESS-GO
XPress the Start/Stop button (Y page 307).
The engine stops and all the indicator
lamps in the instrument cluster go out.
i When the driver's door is closed, this
corresponds to SmartKey position 1. When
the driver's door is open, it corresponds to
SmartKey position 0 or "SmartKey
removed".
i If you use the Start/Stop button to switch
off the engine, the automatic transmission
shifts to N automatically. If you then open
the driver's or front-passenger door, the
automatic transmission shifts to P.
i In an emergency, the engine can be
turned off while the vehicle is in motion by
pressing and holding the Start/Stop button
for 3 seconds. This function operates
independently from the ECO start/stop
automatic engine switch-off function.
Electric parking brake
General informationGWARNING
When leaving the vehicle, always remove the
SmartKey from the starter switch, take it with
you, and lock the vehicle. Do not leave
children unattended in the vehicle, or with
access to an unlocked vehicle. Children could
release the parking brake and/or shift the
automatic transmission out of park position
P , either of which could result in an accident
and/or serious personal injury.
Applying/releasing manually
XTo apply: press handle :.
The red F (USA only) or ! (Canada
only) indicator lamp in the instrument
cluster lights up.
i The electric parking brake can also be
applied when the SmartKey is removed.
XTo release: switch on the ignition.XPull handle :.
The red F (USA only) or ! (Canada
only) indicator lamp in the instrument
cluster goes out.
i The electric parking brake cannot be
released unless the SmartKey is in position
1 in the ignition lock or if the ignition has
been switched on using the Start/Stop
button.
328ParkingDriving and parking