2012 MERCEDES-BENZ G-Class coolant temperature

Display messages Possible causes/consequences and
M Solutionsb
Reversing lamp
right The backup lamp is faulty.
X
Replace the bulb ( Y page 94).b
Tail lamp left
Back-up bulb on
 or 
Tail lamp right
Back-up bulb on The left or right-hand tail lamp is faulty. Another lamp has taken
over its function.
X
Replace the bulb ( Y page 98).Engine
Display messages Possible causes/consequences and
M Solutions; Some electronic systems are unable to send information to the
on-board computer. The coolant temperature gauge and the
tachometer could be malfunctioning.
X
Visit a qualified specialist workshop. +
Top
Up
Coolant See
Operator's Manual The coolant level is too low.
X
Add coolant, following the warning notes when doing so
(Y page 213).
X If coolant needs to be added more often than usual, have the
engine coolant system checked at a qualified specialist
workshop. G
WARNING
Do not spill antifreeze on hot engine parts. Antifreeze contains ethylene glycol which may burn
if it comes into contact with hot engine parts. You could be seriously burned.
! The coolant

level is too low. Avoid making long journeys with too little coolant in the cooling
system. The engine will otherwise be damaged.
The display messages and the corresponding symbol that indicate that the coolant level is
too low must not be ignored. 170
Display messages
On-board computer and displays

Display messages Possible causes/consequences and
M Solutions?
Coolant
Stop,
Turn
Engine Off The coolant is too hot.
X
Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Make sure that the air supply to the radiator is not blocked, e.g.
by snow, slush or ice.
X Wait until the display message disappears before restarting the
engine. Otherwise, there is a risk of engine damage.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visit a qualified specialist
workshop immediately. 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 Open the hood.
X Check whether the poly-V-belt is torn.
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, there is a risk of engine damage.
X Pay attention to the coolant temperature display.
X Visit a qualified specialist workshop. G
WARNING
Driving when your engine is overheated can cause some fluids which may have leaked into the
engine compartment to catch fire. You could be seriously burned.
Steam from

an overheated engine can cause serious burns which can occur just by opening the
engine hood. Stay away from the engine if you see or hear steam coming from it.
Stop the vehicle in a safe location away from other traffic. Turn off the engine, get out of the
vehicle and do not stand near the vehicle until the engine has cooled down.
! If the coolant temperature exceeds 248 ‡(120 †) do not continue driving. The engine will
otherwise be damaged. Display messages
171
On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions? The engine fan is defective.
X
At coolant temperatures under 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-and-go traffic. # The battery is not being charged.
Possible causes are:
R
a defective alternator
R a torn poly-V-belt
R a malfunction in the electronics
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Open the hood.
X Check whether the poly-V-belt is torn.
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 Visit a qualified specialist workshop. The battery voltage is too low.
X
Switch off electrical consumers that are not required.
X Have the battery and alternator checked at a qualified specialist
workshop. The battery has been charged or the vehicle has been jump-
started.
X
Have the battery and alternator checked at a qualified specialist
workshop. 4
Check
oil

level at
next gas station. The engine oil level has dropped to a critical level.
X
Check the oil level (Y page 211).
X If necessary, add engine oil ( Y page 213).
X Have the engine checked for leaks if the engine oil needs to be
refilled more often than usual. You have added too much engine oil. There is a risk of damaging
the engine or catalytic converter.
X
Siphon off excess engine oil until it is at the specified level.
Observe the legal requirements.172
Display messages
On-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 Please read the information on qualified
specialist workshops (Y page 20). Engine compartment
Hood
Opening the hood 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 help prevent personal 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 30 seconds or may even
restart after the engine has been turned off.
Stay clear of fan blades. 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
X Make sure that the windshield wipers are
switched off. 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.
The release lever on the hood is in the footwell
on the left-hand side of the vehicle when
viewed in the direction of travel. 210
Engine compartment
Maintenance and care

X
Turn the SmartKey to position
2(Y page 115) in the ignition lock.
X Check the coolant temperature display in
the instrument cluster.
The coolant temperature must be below
158 ‡ (70 †). G
WARNING
In order to avoid any potentially serious burns:
R use extreme caution when opening the
hood if there are any signs of steam or
coolant leaking
from the cooling system, or
if the coolant temperature display indicates
that the coolant is overheated.
R do not remove the pressure cap on the
coolant reservoir if the coolant temperature
is above 158 ‡ (70 †). Allow the engine to
cool down before removing the cap. The
coolant reservoir contains hot fluid and is
under pressure.
R using a rag, slowly turn the cap
approximately 1
/ 2 turn to relieve excess
pressure. If opened immediately, scalding
hot fluid and steam will be blown out under
pressure.
R do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts. X
Slowly turn cap : half a turn
counterclockwise and allow excess
pressure to escape.
X Turn cap : further counterclockwise and
remove it.
If the coolant is at the level of marker bar
= in the filler neck when cold, there is
enough coolant in coolant expansion
tank ;.
If the coolant is approximately 0.6 in
(1.5 cm) above marker bar = in the filler
neck when warm, there is enough coolant
in coolant expansion tank ;.
X If necessary, add coolant that has been
tested and approved by Mercedes-Benz.
X Replace cap : and

turn it clockwise as far
as it will go.
For further information on coolant, see
(Y page 276).
Windshield washer system and
headlamp cleaning system The washer fluid reservoir is used for both the
windshield
washer

system and the headlamp
cleaning system. G
WARNING
Washer solvent/antifreeze is highly
flammable. Do not spill washer solvent/
antifreeze on

hot engine parts, because it may
ignite and burn. You could be seriously
burned.
! At temperatures below freezing: always
fill the washer fluid reservoir with a mix of
water and windshield washer concentrate
(e.g. MB WinterFit). There is otherwise a
risk of damaging the windshield washer
system/headlamp cleaning system.
! Only use washer fluid concentrate which
is suitable for plastic lenses. Unsuitable
washer fluid concentrate could damage the
plastic lenses of the headlamps. 214
Engine compartment
Maintenance and care

You should have the brake fluid renewed at
regular intervals. The brake fluid change
intervals can be found in the Maintenance
Booklet.
Only use brake fluid approved by Mercedes-
Benz. Information about approved brake
fluids can be obtained from any authorized
Mercedes-Benz Center. Coolant
Important safety notes The coolant is a mixture of water and
antifreeze/corrosion inhibitor. It performs
the following tasks:
R
anti-corrosion protection
R antifreeze protection
R raising the boiling point
The engine cooling system is filled at the
factory with coolant which contains an
antifreeze/corrosion inhibitor that ensures
protection down to approximately -35 ‡
(-37 † ).
! Only add
coolant that has been premixed
with the desired antifreeze protection.
Otherwise, the engine could be damaged.
Further information on coolants and on
filling can be found in the Mercedes-Benz
Specifications for Service Products, MB
Approval 310.1, e.g. on the Internet at
http://bevo.mercedes-benz.com. You can
also consult an authorized Mercedes-Benz
Center.
! 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
the boiling point will be too low.
If the coolant has antifreeze protection down
to -35 ‡ (-37 † ), the boiling point of the
coolant in the pressurized system is
approximately 266 ‡ (130 † ). Your vehicle has a range of aluminum
components. Aluminum components in the
engine make it necessary to use
anticorrosion/antifreeze coolant which has
been specifically formulated to protect the
aluminum parts. Using other antifreeze/
corrosion inhibitors without these
characteristics affects the service life.
The
coolant

must be used throughout the year
in order to maintain the necessary corrosion
protection and provide protection from
overheating. In the Maintenance Booklet, you
can find information on the intervals for
renewal.
The renewal interval is determined by the
coolant type and the engine cooling system
design. The renewal interval in the
Maintenance Booklet is only valid if the
coolant is renewed or replenished with
Mercedes-Benz approved products.
Therefore, only use MB 326.0 antifreeze/
corrosion inhibitor or another Mercedes-Benz
approved product of the same specification.
Information on other products with the same
specifications that are approved by
Mercedes-Benz can be obtained at an
authorized Mercedes-Benz Center or on the
Internet at
http://bevo.mercedes-benz.com.
The coolant is checked at every maintenance
interval at an authorized Mercedes-Benz
Center.
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 to
-49 ‡ [-45 † ]); otherwise, heat will not
dissipate as effectively.
If the coolant level is too low, MB 325.0
antifreeze/corrosion inhibitor should be
added. Have the engine cooling system
checked for possible leaks. 276
Service products and capacities
Technical data