Page 158 of 311
156Climate controlMaintenanceAir intake
The air intake in front of the
windscreen in the engine
compartment must be kept clear to
allow air intake. Remove any leaves,
dirt or snow.
Pollen filter The pollen filter cleans dust, soot,
pollen and spores from the air
entering the vehicle through the air
intake.
Air conditioning regular
operation
In order to ensure continuously
efficient performance, cooling must
be operated for a few minutes once a
month, irrespective of the weather
and time of year. Operation with
cooling is not possible when the
outside temperature is too low.
Service For optimal cooling performance, it is recommended to annually check the
climate control system, starting
three years after initial vehicle
registration, including:
● functionality and pressure test
● heating functionality
● leakage check
● check of drive belts
● cleaning of condenser and evaporator drainage
● performance check
Page 161 of 311

Driving and operating1590:ignition off: Some functions
remain active until key is
removed or driver's door is
opened, provided the ignition was
on previously1:accessory power mode: Steering wheel lock released, some
electrical functions are operable,
ignition is off2:ignition on power mode: Ignition
is on, diesel engine is preheating.
Control indicators illuminate and
most electrical functions are
operable3:engine start: Release key after
starting procedure beginsSteering wheel lock
Remove key from ignition switch and
turn steering wheel until it engages.9 Danger
Never remove the key from
ignition switch during driving as
this will cause steering wheel lock.
Power button
Electronic key must be inside the
vehicle.
Accessory power mode
Press Engine Start/Stop once without
operating clutch or brake pedal. The yellow LED in the button illuminates.
Steering wheel lock is released and
some electrical functions are
operable, ignition is off.Ignition on power mode
Press and hold Engine Start/Stop for
six seconds without operating clutch
or brake pedal. The green LED in the button illuminates, diesel engine is
preheating. Control indicators
illuminate and most electrical
functions are operable.Engine start
Operate clutch pedal (manual
transmission) or brake pedal
(automatic transmission or manual
transmission automated) and press
Engine Start/Stop once more.
Release button after starting
procedure begins.Ignition off
Press Engine Start/Stop briefly in
each mode or when engine is running and vehicle is stationary. Some
Page 163 of 311

Driving and operating161Starting the engine
Vehicles with ignition switch
Turn key to position 1 to release the
steering wheel lock.
Manual transmission: operate clutch
and brake pedal.
Automatic transmission: operate
brake pedal and move selector lever
to P or N.
Manual transmission automated:
operate brake pedal.
Do not operate accelerator pedal.
Diesel engines: turn the key to
position 2 for preheating and wait until
control indicator ! extinguishes.
Turn key briefly to position 3 and
release: an automatic procedure operates the starter with a short delay
until the engine is running, see
Automatic Starter Control.
Manual transmission: during an
Autostop, the engine can be started
by depressing the clutch pedal
3 163.
Automatic transmission or manual
transmission automated: during an
Autostop, the engine can be started
by releasing the brake pedal 3 163.Vehicles with power button
Manual transmission: operate clutch
and brake pedal.
Automatic transmission: operate
brake pedal and move selector lever
to P or N.
Manual transmission automated:
operate brake pedal.
Do not operate accelerator pedal.
Press and release Engine Start/Stop:
an automatic procedure operates the
starter with a short delay until the
engine is running, see automatic
starter control.
Page 166 of 311

164Driving and operatingVehicles with automatic transmission
or manual transmission automated
If the vehicle is at a standstill with
depressed brake pedal, Autostop is
activated automatically.
The engine will be switched off while
the ignition stays on.
The stop-start system will be disabled
on inclines of 15% or more.
Indication
An Autostop is indicated by the
needle at the AUTOSTOP position in
the tachometer.
After restart, the idle speed is
indicated.
During an Autostop, the heating and
brake performance will be
maintained.
Conditions for an Autostop
The stop-start system checks if each
of the following conditions is fulfilled.
● The stop-start system is not manually deactivated.
● The bonnet is fully closed.
● The driver's door is closed or the driver's seat belt is fastened.
● The vehicle battery is sufficiently charged and in good condition.
● The engine is warmed up.
● The engine coolant temperature is not too high.
● The engine exhaust temperature is not too high, e.g. after driving
with high engine load.
● The ambient temperature is above -5 °C.
● The climate control system allows an Autostop.
● The brake vacuum is sufficient.● The self-cleaning function of the diesel particle filter is not active.
● The vehicle was driven at least at
walking speed since the last
Autostop.
Otherwise an Autostop will be
inhibited.
Certain settings of the climate control
system may inhibit an Autostop. See
Climate control chapter for more
details 3 148.
Immediately after motorway driving
an Autostop may be inhibited.
New vehicle running-in 3 158.
Vehicle battery discharge protection
To ensure reliable engine restarts, several vehicle battery discharge
protection features are implemented
as part of the stop-start system.
Power saving measures
During an Autostop, several electrical
features such as auxiliary electric
heater or rear window heating are
disabled or switched to a power
saving mode. The fan speed of the
climate control system is reduced to
save power.
Page 220 of 311

218Driving and operatingSome fuels, mainly high octane
racing fuels, can contain an octane
enhancing additive called
methylcyclopentadienyl manganese
tricarbonyl (MMT). Do not use fuels or fuel additives with MMT as they can
reduce spark plug life and affect
emission control system
performance. The malfunction
indicator light Z may turn on 3 111.
If this occurs, seek the assistance of
a workshop.
Fuel for diesel engines
Only use diesel fuel that complies
with EN 590 and which has a sulphur
concentration of max. 10 ppm.
Fuels with a biodiesel (compliant with
EN 14214) content of max. 7% by
volume may be used (e.g. named
B7).
If travelling in countries outside the
European Union occasional use of
Euro-Diesel fuel with a sulphur
concentration below 50 ppm is
possible.Caution
Frequent usage of diesel fuel containing more than 15 ppm
sulphur will cause severe engine
damage.
Caution
Use of fuel that does not comply to EN 590 or similar can lead to
engine powerloss, increased wear
or engine damage and may affect
your warranty.
Do not use marine diesel oils, heating
oils, Aquazole and similar diesel-
water emulsions. Diesel fuels must
not be diluted with fuels for petrol
engines.
Fuel for natural gas operation
Use natural gas with a methane
content of approx. 78 - 99%. L-gas
(low) has approx. 78 - 87% and H-gas (high) has approx. 87 - 99%. Biogas
with the same methane content can
also be used if it has been chemically
prepared and desulphurised.
Only use natural gas or biogas that complies with DIN 51624.
Liquid gas or LPG must not be used.
Refuelling
Page 250 of 311

248Vehicle careNo.Circuit18Diesel exhaust system19Diesel exhaust system20–21DC/AC Converter22ABS23Washer system for windscreen
and rear window24–25Diesel fuel heating26Transmission control module27Power tailgate module28–29Heated rear window30Mirror defrost31–32DC transformer/LED display/
Electrical heater/Climate
control/Glow plug controllerNo.Circuit33Anti theft warning34Horn35Power outlet load compartment36Right high beam (Halogen)/
Right low beam (LED)37Left high beam (Halogen)38LED headlight/Automatic head‐
light range adjustment39Front fog light40OnStar41Water in fuel sensor/Water
pump42Manual headlight range adjust‐
ment43Fuel pump44Rear view camera/Inside rear
view mirror/Trailer module45LED headlight left/Automatic
headlight range adjustment leftNo.Circuit46Instrument cluster47Steering column lock48Rear wiper49–50LED headlight right/Automatic
headlight range adjustment
right51Left low beam (LED)52Engine control module/Trans‐
mission control module53–54Windscreen wiper55Diesel exhaust system56–57–
After having changed defective fuses,
close the fuse box cover and press
until it engages.
If the fuse box cover is not closed
correctly, malfunction may occur.
Page 252 of 311

250Vehicle careNo.Circuit1–2Climate control system, fan3Power seat driver side4Cigarette lighter/Power outlet
front5–6Power window front7ABS8Heated steering wheel9Body control module10Power window rear11Sunroof12Body control module13Seat heating (only on vehicles
without alarm horn)14Exterior mirror15Body control module16Body control moduleNo.Circuit17Body control module18Body control module19Data link connector20Airbag system21Climate control system22Central locking system, tailgate23Electronic key system24Power seat memory function25Airbag system steering wheel26Ignition switch/Steering column
lock27Body control module28USB socket29–30Selector lever31Rear window wiper32Transmission control moduleNo.Circuit33Anti-theft alarm system/Power
sounder34Parking assist/Side blind spot
alert/Infotainment system/USB
socket35OnStar36Info display/Instrument cluster/ CD player37Infotainment system, radio
After having changed defective fuses,
close the fuse box cover and press
until it engages.
Vehicles with power connector: 1. Apply the cover on the right side.
Page 254 of 311
252Vehicle careNo.Circuit1–2DC/AC Inverter3Trailer module4Power seat passenger side5–6Distance warning module7–8–9Rear seat heating (on vehicles
without alarm horn)10Service11–12Front seat heating (on vehicles
with alarm horn)13Rear seat heating (on vehicles
with alarm horn)14Ignition15Seat ventilationNo.Circuit16Trailer outlet17Trailer outlet18–19–20–21Electrical rear seat folding22Power tailgate
After having changed defective fuses,
close the fuse box cover and press
until it engages.
Additional fuses are located near the
vehicle battery.
No.Circuit1Fuel pump2Engine control module3Power supply