
Engine
Problem
Possible causes/consequences and
M
MSolutions ;
The yellow engine diag-
nostics warning lamp
lights up while the
engine is running. There may be a fault, for example:
R in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system (for vehicles with petrol engines)
R in the fuel system
The emission limit values may be exceeded and the engine may be running in emergency mode.
X Have the vehicle checked as soon as possible at a qualified
specialist workshop. Vehicles with a diesel engine: the fuel tank has been run dry
(Y
page 178).
X Start the engine three to four times after refuelling.
If the yellow engine diagnostics warning lamp goes out, emer-
gency running mode is cancelled. The vehicle need not be
checked. æ
The yellow reserve fuel
warning lamp is on
while the engine is run-
ning.
The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated if the fuel level
drops into the reserve range.
X Refuel at the nearest filling station. ?
The red coolant warn-
ing lamp lights up while
the engine is running
and the coolant tem-
perature gauge is at the start of the scale. The temperature sensor for the coolant temperature gauge is
faulty.
The coolant temperature is no longer being monitored. There is a risk of engine damage if the coolant temperature is too high.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away (Y page 179).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
295On-board computer and displays Z

Problem
Possible causes/consequences and
M
MSolutions X
Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and top up the coolant (Y page 320).
Observe the warning notes as you do so.
X If you have to top up the coolant frequently, have the engine
cooling system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by frozen slush.
X If the coolant temperature is below 120 †, you can continue
driving to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in
mountainous terrain and stop-start traffic. Driving systems
Problem
Possible causes/consequences and
M MSolutions ·
The red distance warn-
ing 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. ·
The red distance warn-
ing 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 about the distance warning function of COL-
LISION PREVENTION ASSIST (Y page 73).
Further information about COLLISION PREVENTION ASSIST PLUS (Y page 76). Warning and indicator lamps in the instrument cluster
297On-board computer and displays Z

wiping noises caused by residue on the wind-
screen.
Washing by hand In some countries, washing by hand is only
allowed at wash bays that are specially
designed for this purpose. Observe the legal
requirements for each individual country.
X Do not use hot water and do not wash the
vehicle in direct sunlight.
X Use a soft sponge to clean.
X Use a mild cleaning agent, such as a car
shampoo approved by Mercedes-Benz.
X Thoroughly hose down the vehicle with a
gentle jet of water.
X Do not point the water jet directly towards
the air inlet.
X Use plenty of water and rinse out the
sponge frequently.
X Rinse the vehicle with clean water and dry
thoroughly with a chamois.
X Do not let the cleaning agent dry on the
paintwork.
When using the vehicle in winter, remove all
traces of road salt deposits carefully and as
soon as possible.
High-pressure cleaning equipment G
WARNING
The water jet of circular-jet nozzles (dirt grind- ers) can cause damage not visible from the
outside to tyres or chassis components. Com-
ponents damaged in this way can unexpect-
edly fail. There is a risk of an accident.
Do not use high-pressure cleaners with circu-
lar-jet nozzles to clean the vehicle. Have dam- aged tyres or chassis components replaced
immediately.
! Always maintain a distance of at least
30 cm between the vehicle and the high-
pressure cleaner nozzle. Information about
the correct distance is available from the
equipment manufacturer. Move the high-pressure cleaner nozzle
around when cleaning your vehicle.
Do not aim directly at any of the following:
R tyres
R door gaps, roof gaps, joints etc.
R electrical components
R battery
R connectors
R lights
R seals
R trim elements
R ventilation slots
Damaged seals or electrical components
can lead to leaks or failures.
! GLA 45 AMG 4MATIC Edition 1 model:
parts of your vehicle are covered with a
decorative foil. Maintain a distance of at
least 70 cm between the foil-wrapped parts
of the vehicle and the nozzle of the high
pressure cleaner.
Information about the correct distance is
available from the equipment manufac-
turer.
Move the high-pressure cleaner nozzle
around when cleaning your vehicle.
Cleaning the wheels !
Do not use acidic wheel cleaning products
to remove brake dust. This could damage
wheel bolts and brake components.
! Do not park up the vehicle for an extended
period straight after cleaning it, particularly after having cleaned the wheels with wheel
cleaner. Wheel cleaners could cause
increased corrosion of the brake discs and
brake pads/linings. For this reason, you
should drive for a few minutes after clean-
ing. Braking heats the brake discs and the
brake pads/linings, thus drying them. The
vehicle can then be parked up. 324
CareMaintenance and care

first be taught-in to the tyre pressure monitor.
If there is a substantial loss of pressure, the
warning threshold for the warning message is aligned to the reference values taught-in.
Restart the tyre pressure monitor after
adjusting to the cold tyre pressure
(Y page 360). The current pressures are
saved as new reference values. This will
ensure that a warning message will only
appear if the tyre pressure drops significantly.
The tyre pressure monitor does not warn you
of an incorrectly set tyre pressure. Observe
the notes on the recommended tyre pressure
(Y page 356).
The tyre pressure monitor is not able to warn
you of a sudden loss of pressure, e.g. if the
tyre is penetrated by a foreign object. In the
event of a sudden loss of pressure, bring the
vehicle to a halt by braking carefully. Avoid
abrupt steering manoeuvres.
The tyre pressure monitor has a yellow warn-
ing lamp in the instrument cluster for indicat- ing a pressure loss or malfunction. Depending
on how the warning lamp flashes or lights up, a tyre pressure that is too low or a malfunc-
tion in the tyre pressure monitor is indicated:
R if the warning lamp is lit continuously, the
tyre pressure on one or more tyres is sig-
nificantly too low. The tyre pressure moni-
tor is not malfunctioning.
R if the warning lamp flashes for around a
minute and then remains lit constantly, the tyre pressure monitor is malfunctioning.
i In addition to the warning lamp, a mes-
sage appears in the multifunction display.
Further information can be found on
(Y page 280).
If the tyre pressure monitor is malfunctioning,
it may take more than ten minutes for the tyre pressure warning lamp to inform you of the
malfunction by flashing for approximately one
minute and then remaining lit. When the fault
has been rectified, the tyre pressure warning lamp goes out after you have driven for a few
minutes. The tyre pressure values indicated by the on-
board computer may differ from those meas-
ured at a filling station using a pressure
gauge. The tyre pressures shown by the on-
board computer refer to those measured at
sea level. At high altitudes, the tyre pressure
values indicated by a pressure gauge are
higher than those shown by the on-board
computer. In this case, do not reduce the tyre
pressures.
The operation of the tyre pressure monitor
can be affected by interference from radio
transmitting equipment (e.g. radio head-
phones, two-way radios) that may be being
operated in or near the vehicle.
Checking the tyre pressure electroni-
cally X
Make sure that the key is in position 2in the
ignition lock (Y page 159).
X Press the =or; button on the steer-
ing wheel to select the Serv. Serv.menu.
X Press the 9or: button to select
Tyre pressure
Tyre pressure.
X Press the abutton.
The current tyre pressure for each wheel
will be displayed in the multifunction dis-
play.
If the vehicle was parked for longer than
20 minutes, the Tyre Tyrepressures
pressures will
willbe
be
displayed after a few minutes of
displayed after a few minutes of
driving driving message is shown.
After a teach-in period, the tyre pressure
monitor automatically detects new wheels or new sensors. As long as a clear allocation of
the tyre pressure values to the individual
wheels is not possible, the Tyre pressure Tyre pressure
monitor active
monitor active message is shown instead
of the tyre pressure display. The tyre pres-
sures are already being monitored.
i If an emergency spare wheel is fitted, for
a few minutes the system may continue to
show the tyre pressure of the wheel that
has been removed. If this occurs, note that
the value displayed for the position where Tyre pressure
359Wheels and tyres Z