152Driving and operatingNotice
The system may be switched off if it
detects lanes which are too narrow,
too wide or too curved.
Following preconditions have to be
fulfilled:
● vehicle speed must be between 40 mph and 112 mph
● the driver must hold the steering wheel
● the turn lights are not activated ● the electronic stability control is activated and not in operation
● the vehicle is not connected to a trailer or an electric bicycle carrier
● normal driving behaviour (system
detects dynamic driving style, i.e. pressure on the brake or
accelerator pedal)
● roads with good lane markings ● no spare wheel is used
● the driver is not taking the hands off the steering wheel for a longer
time period
● the vehicle is not driven in a tight
cornerActivation
If the system is activated, the LED in
the button j is not illuminated. To
activate the system when the system
is deactivated, press j.
The system is operational at vehicle
speeds between 40 mph and
112 mph and if lane markings are
detectable. The driver must hold the
steering wheel. The electronic
stability control system must be
activated.
The control indicator L flashes
yellow during trajectory correction.
If the driver wishes to maintain the
trajectory of the vehicle, he can
interrupt the correction by keeping a
firm grip on the steering wheel, e.g.
during an avoiding manoeuvre. The
correction is interrupted if the turn
lights are operated. If the vehicle is
equipped with active side blind spot detection, the interruption of the lane
correction might be cancelled.
Side blind zone assistant 3 145.
There is no correction triggered when
the turn lights are operated and
during few seconds after turn lights
have been switched off.
If the system detects that the driver is not holding the steering wheel
permanently, it interrupts the
correction. A warning message in the
Driver Information Centre
accompanied by a warning chime
alerts the driver when immediate
driver´s action is required.
Driving and operating153DeactivationTo deactivate the system, press and
hold j. Deactivation of the system is
confirmed by the illuminated LED in
the button and L illuminates yellow
in the instrument cluster.
Fault
In the event of a fault, L and C
appear in the instrument panel,
accompanied by a display message
and a warning chime. Contact a
dealer or a qualified workshop to have the system checked.
System limitations The system performance may be
affected by:
● a dirty or foggy windscreen or if the windscreen is affected by
foreign objects, e.g. stickers
● close vehicles ahead
● banked roads
● winding or hilly roads
● road edges
● sudden lighting changes● adverse environmental conditions, e.g. heavy rain or
snow
● vehicle modifications, e.g. tyres
Switch off the system if the system is
disturbed by tar marks, shadows,
road cracks, temporary or
construction lane markings, or other
road imperfections.9 Warning
Always keep your attention on the
road and maintain proper vehicle
position within the lane, otherwise
vehicle damage, injury or death
could occur.
Lane keep assist does not
continuously steer the vehicle.
The system may not keep the
vehicle in the lane or give an alert,
even if a lane marking is detected.
The steering of the lane keep
assist may not be sufficient to
avoid a lane departure.
The system may not detect hands-
off driving due to external
influences like road condition and
surface and weather. The driver has full responsibility to control the vehicle and is always required to
keep the hands on the steering
wheel while driving.
Using the system while towing a
trailer or on slippery roads could
cause loss of control of the vehicle
and a crash. Switch the system off.
Driver alert
The driver alert system monitores the driving time and the vigilance of the
driver. Monitoring the vigilance of the
driver is based on the trajectory
variations of the vehicle compared to
the lane markings.
The system includes a driving time
alert combined with driver drowsiness detection.
154Driving and operating9Warning
The system cannot replace the
need for vigilance on the part of
the driver. Taking a break is
recommended as soon as feeling tired or at least every 2 hours. Do
not drive when feeling tired.
Activation or Deactivation
The system can be activated or
deactivated in the vehicle
personalisation 3 76.
The state of the system stays in
memory when the ignition is switched
off.
Driving time alert
The driver gets notified by a pop-up reminder symbol € in the Driver
Information Centre simultaneously
with an acoustic alert if the driver has
not taken a break after 2 hours of
driving at a speed above 40 mph. The alert is repeated hourly until the
vehicle is stopped, no matter how
vehicle speed evolves.
The counting of driving time alert is
reset when the ignition has been
switched off for a few minutes.
Driver drowsiness detection The system monitors the driver's level
of vigilance at speeds above 40 mph.
A camera at the top of the windscreen detects variations in trajectory
compared to the lane markings.
If the trajectory of the vehicle
suggests a certain level of
drowsiness or inattention by the
driver, the system triggers the first
level of alert. The driver is notified by
a message and an audible signal is
given.
After three first level alerts, the
system triggers a new alert with a message, accompanied by a more
pronounced audible signal.
In certain driving conditions (poor
road surface or strong winds), the
system may give alerts independent
of the driver's level of vigilance.The driver drowsiness detection is
reinitialised when the ignition has
been switched off for a few minutes or the speed remains below 40 mph for
a few minutes.
System limitations
In the following situations, the system
may not operate properly or even not operate at all:
● poor visibility caused by inadequate lighting of the
roadway, falling snow, heavy
rain, dense fog etc.
● dazzle caused by headlamps of an oncoming vehicles, low sun,
reflections on damp roads,
leaving a tunnel, alternating
shade and light etc.
● windscreen area in front of the camera covered by dirt, snow,
stickers etc.
● no lane markings detected or multiple lane markings due to
roadworks
● close vehicles ahead
● winding roads or narrow roads
162Vehicle careVehicle checks
Performing work9 Warning
Only perform engine compartment
checks when the ignition is off.
The cooling fan may start
operating even if the ignition is off.
9 Danger
The ignition system uses
extremely high voltage. Do not
touch.
Bonnet
Opening
Open the driver's door.
Pull the release lever and return it to
its original position.
Push the safety catch upwards and
open the bonnet.
Secure the bonnet support.
164Vehicle care
The engine oil level must not exceed
the MAX mark on the dipstick.
Caution
Overfilled engine oil must be
drained or suctioned out. If the oil exceeds the maximum level, do
not start the vehicle and contact a
workshop.
Capacities 3 207.
Fit the cap on straight and tighten it.
Engine coolant
The factory filled coolant provides
freeze protection down to approx.
-37 °C.Caution
Only use approved antifreeze.
Coolant and antifreeze 3 199.
Coolant level
Caution
Too low a coolant level can cause engine damage.
If the cooling system is cold, the
coolant level should be above the
MIN mark. Top up if the level is low.
9Warning
Allow the engine to cool before
opening the cap. Carefully open
the cap, relieving the pressure
slowly.
To top up, use a 1:1 mixture of
released coolant concentrate mixed
with clean tap water. If no coolant
concentrate is available, use clean
tap water. Install the cap tightly. Have
Vehicle care165the coolant concentration checked
and have the cause of the coolant
loss remedied by a workshop.
Washer fluid
Fill with clean water mixed with a
suitable quantity of approved
windscreen washer fluid which
contains antifreeze.
Caution
Only washer fluid with a sufficient
antifreeze concentration provides
protection at low temperatures or
a sudden drop in temperature.
Washer fluid 3 199.
Brakes In the event of minimum thickness of
the brake lining, a squealing noise
sounds during braking.
Continued driving is possible but
have the brake lining replaced as
soon as possible.
Once new brake linings are installed,
do not brake unnecessarily hard for
the first few journeys.
Brake fluid9 Warning
Brake fluid is poisonous and
corrosive. Avoid contact with eyes, skin, fabrics and painted surfaces.
The brake fluid level must be betweenthe MIN and MAX marks.
If fluid level is below MIN seek the
assistance of a workshop.
Brake and clutch fluid 3 199.
Vehicle battery
The vehicle battery is maintenance-
free provided that the driving profile
allows sufficient charging of the
battery. Short-distance-driving and
frequent engine starts can discharge
the battery. Avoid the use of
unnecessary electrical consumers.
166Vehicle care
Batteries do not belong in household
waste. They must be disposed of at
an appropriate recycling collection
point.
Laying up the vehicle for more than
four weeks can lead to battery
discharge. Disconnect the clamp from the negative terminal of the vehicle
battery.
Ensure the ignition is switched off
before connecting or disconnecting
the vehicle battery.
Battery discharge protection 3 87.
Replacing the vehicle battery Notice
Any deviation from the instructions
given in this section may lead to
temporary deactivation or
disturbance of the stop-start system.
When the vehicle battery is being
replaced, please ensure that there
are no open ventilation holes in the
vicinity of the positive terminal. If a
ventilation hole is open in this area, it
must be closed off with a dummy cap, and the ventilation in the vicinity of the
negative terminal must be opened.
Ensure that the battery is always
replaced by the same type of battery.
The vehicle battery has to be
replaced by a workshop.
Stop-start system 3 102.
Charging the vehicle battery9 Warning
On vehicles with stop-start
system, ensure that the charging potential does not exceed 14.6 V
when using a battery charger.
Otherwise the vehicle battery may be damaged.
Jump starting 3 189.
Discharge protection
Battery voltage
When the vehicle battery voltage is
running low, a warning message will
appear in the Driver Information
Centre.
When the vehicle is being driven, the
load reduction function temporarily
deactivates certain functions, such as
the air conditioning, the heated rear
window, heated steering wheel, etc.
The deactivated functions are
reactivated automatically as soon as
conditions permit.
Idle boost
If charging of the vehicle battery is
required due to battery condition, the
power output of the generator must
be increased. This will be achieved by
an idle boost which may be audible.
A message appears in the Driver
Information Centre.
Power outlet
The power outlets are deactivated in
the event of low vehicle battery
voltage.
Vehicle care167Warning label
Meaning of symbols:● No sparks, naked flames or smoking.
● Always shield eyes. Explosive gases can cause blindness or
injury.
● The vehicle battery contains sulphuric acid which could cause
blindness or serious burn
injuries.
● Keep the vehicle battery out of reach of children.
● See the Owner's Manual for further information.
● Explosive gas may be present in the vicinity of the vehicle battery.
Power saving mode This mode deactivates electrical
consumers to avoid excessive
discharging of the vehicle battery.
These consumers, such as the
Infotainment system, windscreen
wipers, low beam headlights,
courtesy light, etc. can be used for a
total maximum time of about
40 minutes after ignition is switched
off.
Changing into power saving mode
When power saving mode is
activated, a message appears in the
Driver Information Centre.
An active telephone call using the
hands-free option will be maintained
for around 10 minutes longer.Deactivating power saving mode
Power saving mode is deactivatedautomatically when the engine is
restarted. Run the engine for a
sufficient charge:
● for less than 10 minutes to use the consumers for approx.
5 minutes
● for more than 10 minutes to use the consumers for up to approx.
30 minutes
Heating functionalities Notice
Individual heating functionalities,
such as heated seats or heated
steering wheel, may be temporarily
unavailable in the event of electrical
loading constraints. Functions will be resumed after some minutes.