
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 160).
X Wait 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 †). 244
Display messages
On-board computer and displays

Problem Possible causes/consequences and
0050 Solutions00AC
The red coolant
warning lamp lights up
while the engine is
running and the coolant
temperature gauge is
at
the
start of the scale. The temperature sensor for the coolant temperature gauge is
defective.
The
coolant temperature
is no
longer being monitored. There is a
risk of engine damage if the coolant temperature is too high.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and
traffic conditions. Do not continue
driving under any circumstances.
X Secure the vehicle against rolling away ( Y page 160).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
265
On-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.
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 Secure the vehicle against rolling away ( Y page 160).
X Wait 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 Check the coolant level and add coolant (Y page 302). Observe
the warning notes.
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X At coolant temperatures below 248 ‡ (120 †) drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic. 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.
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 Secure the vehicle against rolling away ( Y page 160).
X Wait until the engine has cooled down.266
Warning and indicator lamps in the instrument cluster
On-board computer and displays

Problem Possible causes/consequences and
0050 SolutionsX
Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X Check the coolant level and add coolant (Y page 302). Observe
the warning notes.
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X At coolant temperatures below 248 ‡ (120 †) drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic. Driving systems
Problem Possible causes/consequences and
0050 Solutions00BA
The red distance
warning lamp lights up
while the vehicle is in
motion.
G
WARNING
The distance to the vehicle in front is too small for the speed
selected.
There is a risk of an accident.
X Increase the distance. 00BA
The red distance
warning lamp lights up
while the vehicle is in
motion. A warning tone
also sounds. G
WARNING
You are approaching a vehicle or a stationary obstacle in your line
of travel at too high a speed.
There is a risk of an accident.
X Be prepared to brake immediately.
X Pay careful attention to the traffic situation. You may have to
brake or take evasive action.
More information about DISTRONIC PLUS (Y page 171) and
PRE-SAFE ®
Brake (Y page 69). Warning and indicator lamps in the instrument cluster
267On-board computer and displays Z

Damage to the engine or exhaust system is
caused by the following:
R
using engine oils and oil
filters that have
not been specifically approved for the
service system
R replacing engine oil and oil filters after
the interval for replacement specified by
the service system has been exceeded
R using engine oil additives.
! Do not add too much oil. If the oil level is
above the "max" mark on the dipstick, too
much oil has been added. This can lead to
damage to the engine or the catalytic
converter. Have excess oil siphoned off. Example: engine oil cap
X
Turn cap 0043 counter-clockwise and remove
it.
X Add engine oil.
If the oil level is at or below the MIN mark
on the oil dipstick, add
1.1 US qt (1.0 liter)
of engine oil.
X Replace cap 0043 on the filler neck and turn
clockwise.
Ensure that the cap locks into place
securely.
X Check the oil level again with the oil
dipstick (Y page 301).
Further information on engine oil
(Y page 369). Checking and adding other service
products
Checking coolant level G
WARNING
The engine cooling system is pressurized,
particularly when the engine is warm. When
opening the cap, you could
be scalded by hot
coolant spraying out. There is a risk of injury.
Let the engine cool down before opening the
cap. Wear eye and hand protection when
opening the cap. Open the cap slowly half a
turn to allow pressure to escape.
Only check the coolant level when the vehicle
is on a level surface and the engine has cooled
down.
X Turn the SmartKey to position 2 in the
ignition lock (Y page 141).
On vehicles with KEYLESS-GO, press the
Start/Stop button twice (Y
page 141).
X Check the coolant temperature display in
the instrument cluster.
The coolant temperature must be below
158 ‡ (70 †). X
Slowly turn cap 0043 half a turn counter-
clockwise and allow excess pressure to
escape.
X Turn cap 0043 further
counter-clockwise and
remove it.
If the coolant is at the level of marker bar
0087 in the filler neck when cold, there is
enough coolant in coolant expansion
tank 0044
.302
Engine compartment
Maintenance and care

If the coolant level is approximately 0.6 in
(1.5 cm) above marker bar
0087 in the fuel
filler neck when warm, there is enough
coolant in expansion tank 0044.
X If necessary, add coolant that has been
tested and approved by Mercedes-Benz.
X Replace cap 0043
and turn it
clockwise
as far
as it will go.
For further information on coolant, see
(Y page 371).
Adding washer fluid to the windshield
washer system/headlamp cleaning
system G
WARNING
Windshield washer concentrate is highly
flammable. If it comes into contact with hot
engine components or the exhaust system it
could ignite. There is a risk of fire and injury.
Make sure that no windshield washer
concentrate is spilled next to the filler neck. X
To open: pull cap 0043 upwards by the tab.
X Add the premixed washer fluid.
X To close:
press cap 0043 onto the
filler neck
until it engages.
The washer fluid reservoir is used for both the
windshield washer system and the
headlamp
cleaning system.
The recommended minimum amount when
topping up is 1 liter. If the water level drops
below this, a message appears in the
multifunction display prompting you to refill
the washer fluid ( Y page 255). Further information on windshield washer
fluid/antifreeze (
Y page 372). Care
General notes
! For cleaning your vehicle, do not use any
of the following:
R dry, rough or hard cloths
R abrasive cleaning agents
R solvents
R cleaning agents containing solvents
Do not scrub.
Do not touch the surfaces or protective
films with hard objects, e.g. a ring or ice
scraper. You could otherwise scratch or
damage the surfaces and protective film. H
Environmental note
Dispose of empty packaging and cleaning
cloths in an environmentally responsible
manner.
! Do not park 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
cleaning. Braking heats the brake discs and
the brake pads/linings, thus drying them.
The vehicle can then be parked.
Regular care of your vehicle is a condition for
retaining the quality in the long term.
Use care products and cleaning agents
recommended and approved by Mercedes-
Benz. Care
303Maintenance and care Z

H
Environmental note
Dispose of service products in an
environmentally responsible manner.
Service products include the following:
R Fuels (e.g. gasoline, diesel)
R Exhaust gas aftertreatment additives, e.g.
DEF
R Lubricants (e.g. engine oil, transmission
oil)
R Coolant
R Brake fluid
R Windshield washer fluid
R Climate control system refrigerant
Comply with all valid regulations with respect
to handling, storing, and disposing of service
fluids.
Components and service products must be
matched. You should therefore only use
products that have been tested and approved
by Mercedes-Benz.
Information about tested and approved
products can be obtained from an authorized
Mercedes-Benz Center or on the Internet at
http://bevo.mercedes-benz.com.
You can recognize service products approved
by Mercedes-Benz by the following
inscription on the containers:
R MB-Freigabe (e.g. MB-Freigabe 229.51)
R MB Approval (e.g. MB Approval 229.51)
Other designations or recommendations
indicate a level of quality or a specification in
accordance with an MB Sheet number (e.g.
MB 229.5). They have not necessarily been
approved by Mercedes-Benz. Fuel
Important safety notes G
WARNING
Fuel is highly flammable. If you handle fuel
incorrectly, there is a risk of fire and
explosion. You must avoid fire, open flames, creating
sparks and smoking. Switch off the engine
and, if applicable, the
auxiliary
heating before
refueling. G
WARNING
Fuel is poisonous and hazardous to health.
There is a risk of injury.
You must make sure that
fuel does not come
into contact with your skin, eyes or clothing
and that it is not swallowed. Do not inhale fuel
vapors. Keep fuel away from children.
If you or others come into contact with fuel,
observe the following:
R Wash away fuel from skin immediately
using soap and water.
R If fuel comes into contact with your eyes,
immediately rinse them thoroughly with
clean water. Seek medical assistance
without delay.
R If fuel is swallowed, seek medical
assistance without delay. Do not induce
vomiting.
R Immediately change out of clothing which
has come into contact with fuel.
Tank capacity Model Total
capacity GLK 250 BlueTEC
15.6 US gal
(59.0 l) All other models
17.4 US gal
(66.0 l) Model Of which
reserve All models
approx.
2.1 US gal (8.0 l)366
Service products and filling capacities
Technical data

Coolant
Important safety notes G
WARNING
If antifreeze comes into contact with hot
components in the engine compartment, it
may ignite. There is a risk of fire and injury.
Let the engine cool down before you add
antifreeze. Make sure that antifreeze is not
spilled next to the filler neck. Thoroughly
clean the antifreeze from components
before
starting the engine.
! Only add coolant that has been premixed
with the desired antifreeze protection. You
could otherwise damage the engine.
Further information on coolants can be
found in the Mercedes-Benz Specifications
for Service Products, MB Specifications for
Service Products 310.1, e.g. on the
Internet at
http://bevo.mercedes-benz.com. Or
contact a qualified specialist workshop.
! Always use a suitable coolant mixture,
even in countries where high temperatures
prevail.
Otherwise, the engine cooling system is not
sufficiently protected from corrosion and
overheating.
When handling coolant, observe the
important safety notes on service products
(Y page 365).
The coolant is a mixture of water and
antifreeze/corrosion inhibitor. It performs
the following tasks:
R corrosion protection
R antifreeze protection
R raising the boiling point
If the coolant has antifreeze protection down
to -35 ‡ (-37 †), the boiling point of the
coolant during operation is approximately
266 ‡ (130 †). The antifreeze/corrosion inhibitor
concentration in the engine cooling system
should:
R
be at least 50%. This
will protect the engine
cooling system against freezing down to
approximately -35 ‡ (-37 †).
R not exceed 55% (antifreeze protection
down to -49 ‡ [-45 †]). Otherwise, heat
will not be dissipated as effectively.
If the vehicle has lost coolant, add equal
amounts of water and antifreeze/corrosion
inhibitor.
Mercedes-Benz recommends an antifreeze/
corrosion inhibitor concentrate in
accordance with MB Specifications for
Service Products 310.1.
The coolant is checked with every
maintenance interval at a qualified specialist
workshop.
i When the vehicle is first delivered, it is
filled with a coolant mixture that ensures
adequate antifreeze and corrosion
protection.
Filling capacities Model Capacity
GLK 250 BlueTEC
approx. 10.6 US qt
(10.0 l) GLK 350
BlueEFFICIENCY
GLK 350 4MATIC
BlueEFFICIENCY
approx. 8.9 US qt
(8.4 l) i
Use MB 325.0 or MB 326.0 corrosion
inhibitor/antifreeze. Service products and filling capacities
371
Technical data Z