
Problem Possible causes/consequences and
0050 SolutionsThe coolant
temperature display is
showing more than
248 ‡
(120 †). A
display message may
also appear in the
multifunction display
and a
warning
tone may
sound. The coolant level is too low. The coolant is too hot and the engine
is no longer being cooled sufficiently.
X
Stop as soon as possible and allow the engine and the coolant
to cool down.
X Check the coolant level (Y page 291). Observe the warning
notes as you do so and add coolant if necessary. If the coolant level is correct, the radiator fan may be faulty. The
coolant is too hot and the engine is no longer being cooled
sufficiently.
X
At coolant temperatures below 248 ‡ (120 †),
drive
to the next
qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in
mountainous terrain and stop-and-go traffic. Automatic transmission
Important safety notes
G
WARNING
If the engine speed is above the idling speed
and you engage transmission position D or
R, the vehicle could
pull away suddenly. There
is a risk of an accident.
When engaging transmission position D or R,
always firmly depress the brake pedal and do
not simultaneously accelerate. G
WARNING
The automatic transmission switches to
neutral position N when you switch off the
engine. The vehicle may roll away. There is a
risk of an accident.
After switching off the engine, always switch
to parking position P. Prevent the parked
vehicle from rolling away by applying the
parking brake.
i Bear in mind that
the power transmission
between the engine and the transmission
is interrupted when the engine is switched
off. Therefore, to prevent the vehicle from
rolling away, shift the automatic
transmission to position P and apply theparking brake when the engine is switched
off and the vehicle is stationary.
Selector lever
Overview of transmission positions !
If the engine speed is too high or if the
vehicle is rolling, do not shift the
transmission directly from D to R, from R
to D or directly to P.
Do not open the driver's door while the
vehicle is in motion. At low speeds in
transmission position D or R
, park position
P is otherwise engaged automatically.
The transmission could be damaged. Automatic transmission
145
Driving and parking Z

Active Blind Spot Assist monitors the area up
to 10 ft (3.0 m) behind your vehicle and
directly next to your vehicle, as shown in the
diagram. For this purpose, Active Blind Spot
Assist uses radar
sensors in the rear bumper.
If the lanes are narrow, vehicles driving in the
lane beyond the lane next to your vehicle may
be indicated, especially if the vehicles are not
driving in the middle of their lane. This may
be the case if there are vehicles driving at the
inner edge of their lanes.
Due to the nature of the system:
R warnings may be issued in error when
driving close to crash barriers or similar
solid lane borders.
R warnings may be interrupted when driving
alongside particularly long vehicles, for
example trucks, for a prolonged time.
Two Active Blind Spot Assist radar sensors
are integrated into the front and rear bumpers
respectively. An additional radar sensor is
located behind the cover in the radiator grill.
Make sure that the bumpers and the cover in
the radiator grill are free of dirt, ice or slush.
The rear sensors must not be covered, for
example by cycle racks or overhanging cargo.
Following a severe impact or in the event of
damage to the bumpers, have the function of
the radar sensors checked at a qualified specialist workshop. Active Blind Spot Assist
may otherwise no longer work properly.
Indicator and warning display
G
WARNING
Active Blind Spot Assist is not active at speeds
below 20 mph (
30km/h). The indicator lamps
in the exterior mirrors are yellow. Vehicles in
the monitoring range are then not indicated.
Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others. 0043
Yellow indicator lamp/red warning lamp
When Active Blind Spot Assist is activated,
indicator lamp
0043
in
the exterior mirrors lights
up yellow at speeds of up to 20 mph
(30 km/h). At speeds above
20 mph(30 km/h), the indicator lamp goes
out and Active Blind Spot Assist is
operational.
If a vehicle is detected within the monitoring
range of Blind Spot Assist at speeds above
20 mph (30 km/h), warning lamp 0043 on the
corresponding side lights up red. This warning
is always emitted when a vehicle enters the
blind spot monitoring range from behind or
from the side. When you overtake a vehicle,
the warning only occurs if the difference in
speed is less than 7 mph (12 km/h).
The yellow indicator lamp goes out if reverse
gear is engaged. In this event, Active Blind
Spot Assist is no longer active. 190
Driving systems
Driving and parking

Display messages Possible causes/consequences and
0050 Solutions00AC
Coolant Too Hot
Stop Vehicle Turn
Engine Off The coolant is too hot.
A warning tone also sounds.
G WARNING
Do not drive when your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to
catch fire.
Steam from the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Y page 156).
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X Do not start the engine again until the display message goes out
and the coolant temperature is below 248 ‡ (120 †).
Otherwise, the engine could be damaged.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visit a qualified specialist
workshop immediately.
Under normal
operating conditions and with the specified coolant
level, the coolant temperature may rise to 248 ‡ (120 †). The poly-V-belt may have torn.
X
Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Check the poly-V-belt.
If the poly-V-belt is torn:
! Do not continue driving.
The engine could otherwise overheat.
X Consult a qualified specialist workshop.
If the poly-V-belt is not damaged:
X Wait until the display message disappears before restarting the
engine. Otherwise, the engine could be damaged.
X Pay attention to the coolant temperature display.
X Visit a qualified specialist workshop. Display messages
235
On-board computer and displays Z

Display messages Possible causes/consequences and
0050 SolutionsDISTRONIC PLUS
Currently
Unavailable See
Operator's Manual DISTRONIC is deactivated and temporarily inoperative. Possible
causes are:
R
the DISTRONIC PLUS cover in the radiator trim is dirty
R function is impaired due to heavy rain or snow.
R the sensors in the bumpers are dirty.
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio
stations or other sources of electromagnetic radiation.
R the system is outside the operating temperature range.
R the transfer case is in the LOW RANGE transmission position.
R the vehicle is on an uphill or downhill gradient of greater than
22%-25%.
R the on-board voltage is too low.
A warning tone also sounds.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Apply the parking brake.
X Clean the DISTRONIC PLUS cover in the radiator trim and the
bumper ( Y page 297).
X Restart the engine.
If the system detects that the sensors are fully operational, the
display message disappears.
DISTRONIC is operational again. DISTRONIC PLUS
Inoperative DISTRONIC PLUS is defective.
BAS (Brake Assist) may also have failed.
A warning tone also sounds.
X
Visit a qualified specialist workshop. DISTRONIC PLUS
Passive You have depressed the accelerator pedal. DISTRONIC PLUS is no
longer controlling the speed of the vehicle.
X
Remove your foot from the accelerator pedal. DISTRONIC PLUS
--- mph An activation condition for DISTRONIC PLUS is not fulfilled.
X
Check the activation conditions for DISTRONIC PLUS
(Y page 177). DISTRONIC PLUS and
SPEEDTRONIC
Inoperative DISTRONIC PLUS and SPEEDTRONIC are faulty. A warning tone
also sounds.
X
Visit a qualified specialist workshop. Display messages
241On-board computer and displays Z

Problem Possible causes/consequences and
0050 Solutions00AC
The red coolant
warning lamp comes
on
while the engine is
running. The coolant level is too low.
!
Avoid making long
journeys
with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
If the coolant level is correct, the airflow to the engine radiator
may be blocked or the electric engine radiator fan may be
malfunctioning.
The coolant is too hot and the engine is no longer being cooled
sufficiently.
X Observe the additional display messages in the multifunction
display.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Apply the parking brake.
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and add coolant, observing the warning
notes (Y page 291).
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X Do not start the engine again until the coolant temperature is
below 248 ‡ (120
†). Otherwise, the engine could be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-start driving. 00AC
The red coolant
warning lamp comes
on
while the engine is
running.
A warning tone
also sounds. The coolant temperature has exceeded 248 ‡ (120 †). The
airflow
to the
engine
radiator may be blocked or the coolant level
may be too low.
G WARNING
The engine is not being cooled sufficiently and may be damaged.
Do not drive when
your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to
catch fire.
Steam from the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury. Warning and indicator lamps in the instrument cluster
257
On-board computer and displays Z

Problem Possible causes/consequences and
0050 SolutionsX
Observe the additional display messages in the multifunction
display.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away ( Y page 156).
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and add coolant, observing the warning
notes (Y page 291).
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X At coolant temperatures below 248 ‡ (120 †),
drive to the next
qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-start driving. Driving systems
Problem Possible causes/consequences and
0050 Solutions00BA
The red distance
warning lamp lights up
while the vehicle is in
motion.
The distance to the vehicle in front is too small for the speed
selected.
X
Increase the distance. 00BA
The red distance
warning lamp lights up
while the vehicle is in
motion. A warning
tone
also sounds. You are approaching a vehicle or a stationary obstacle in your line
of travel at too high a speed.
X
Be prepared to brake immediately.
X Pay careful attention to the traffic situation. You may have to
brake or take evasive action.
Further information on DISTRONIC PLUS ( Y page 177).258
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Useful information
i This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences are
possible. Please note that
your vehicle may
not be equipped with all features
described. This also applies to safety-
related systems and functions.
i Read the information on qualified
specialist workshops: ( Y page 23).Engine compartment
Hood
Important safety notes G
WARNING
Do not pull the release lever while the vehicle
is in motion. Otherwise, the hood could be
forced open by passing air flow.
This could cause the
hood to come loose and
injure you and/or others. G
WARNING
Do not open the hood when the engine is
overheated. You could be seriously injured.
Observe the coolant temperature gauge to
determine whether the engine may be
overheated. If you see flames or smoke
coming from the engine compartment, move
away from the vehicle. Wait until the engine
has cooled. If necessary, call the fire
department. G
WARNING
You could be injured when the hood is open –
even when the engine is turned off.
Parts of the engine can become very hot. To
prevent burns, let
the
engine cool completely
before touching any components on the
vehicle. Comply with all relevant safety
precautions. G
WARNING
To avoid injury, stay clear of moving parts
when the hood is open and the engine is
running.
The radiator fan may continue to run for
approximately 30seconds or may even
restart
after the engine has been switched off. For
this reason, you must not reach into the fan
rotation area. G
WARNING
The engine is equipped with a transistorized
ignition system. Because of the high voltage,
it is dangerous to touch any components
(ignition coils, spark plug sockets, diagnostic
socket) of the ignition system:
R with the engine running
R while starting the engine
R when the ignition is switched on and the
engine is turned manually G
WARNING
The windshield wipers and wiper linkage
could be set in motion.
When the hood is open, you or others could
be injured by the wiper linkage.
Make sure that the windshield wipers are
switched off and that
the SmartKey has been
pulled out of the ignition lock before opening
the hood.
! Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield
wipers or the hood. 288
Engine compartment
Maintenance and care