142Driving and operatingCaution
Fuel grades other than those listedon pages 3 168, 3 229 could
damage the catalytic converter or
electronic components.
Unburnt petrol will overheat and
damage the catalytic converter.
Therefore avoid excessive use of the starter, running the fuel tank
dry and starting the engine by
pushing or towing.
In the event of misfiring, uneven
engine running, a reduction in engine performance or other unusual
problems, have the cause of the fault
rectified by a workshop as soon as
possible. In an emergency, driving
can be continued for a short period,
keeping vehicle speed and engine
speed low.
AdBlue
General information
The selective catalytic reduction
(BlueInjection) is a method to
substantially reduce the nitrogen
oxides in the exhaust emission. This
is achieved by injecting a Diesel
Exhaust Fluid into the exhaust
system. The ammonia released by
the fluid reacts with nitrous gases
(NO x) from the exhaust and turns it
into nitrogen and water.
The designation of this fluid is AdBlue
® . It is a non-toxic, non-flammable,
colourless and odourless fluid which
consists of 32% urea and 68% water.9Warning
Avoid contact of your eyes or skin
with AdBlue.
In case of eye or skin contact,
rinse off with water.
Caution
Avoid contact of the paintwork with AdBlue.
In case of contact, rinse off with water.
AdBlue freezes at a temperature of
approx. -11 °C. As the vehicle is
equipped with an AdBlue pre-heater,
the emissions reduction at low
temperatures is ensured. The AdBlue
pre-heater works automatically.
The typical AdBlue consumption is
approx. 2 l per 600 miles, but can also be higher depending on driving
behaviour (e.g. high load or towing).
AdBlue tank The AdBlue tank level can be found in the display menu.
Level warnings
Depending on the calculated range of
AdBlue, different messages are
displayed in the Driver Information
Centre. The messages and the
restrictions are a legal requirement.
Driving and operating149Drive systems
All-wheel drive
The All-Wheel Drive (AWD) system
enhances driving characteristics and
stability, and helps to achieve the best possible driveability regardless of
ground surface. The system is always
active and cannot be deactivated.
The torque is distributed steplessly
between the wheels of the front and
rear axle, depending on the driving
conditions. Additionally the torque
between the rear wheels is distributed
depending on the surface.
For optimum system performance,
the vehicle's tyres should not have
varying degrees of wear.
When using a temporary spare
wheel, the AWD system is
automatically disabled.
The AWD system will also be
temporarily disabled to protect the
system from overheating if there is
excessive wheel spin. When the
system cools down, AWD will be
restored.The deactivation of the AWD system
will be indicated by a message on the
Driver Information Centre.
If a service message or warning
code S73 is displayed on the Driver Information Centre, there is a
malfunction in the AWD system. Seek the assistance of a workshop.
Vehicle messages 3 102.
Towing the vehicle 3 214.Brakes
The brake system comprises two
independent brake circuits.
If a brake circuit fails, the vehicle can
still be braked using the other brake
circuit. However, braking effect is
achieved only when the brake pedal
is depressed firmly. Considerably
more force is needed for this. The
braking distance is extended. Seek the assistance of a workshop before
continuing the journey.
When the engine is not running, the
support of the brake servo unit
disappears once the brake pedal has
been depressed once or twice.
Braking effect is not reduced, but
braking requires significantly greater
force. It is especially important to bear this in mind when being towed.
Control indicator R 3 91.
Antilock brake system
Antilock brake system (ABS)
prevents the wheels from locking.
