2020 MERCEDES-BENZ METRIS coolant temperature

Engine
Warning/
indicator
lamp
N Signal type
Possible causes/consequences and
M Solutions;
N The yellow Check Engine warning lamp lights up while the engine is running.
There may be a malfunction in the following vehicle systems:
R in the engine management
R in the transmission management
R in the fuel injection system
R in the exhaust system
R in the ignition system (for vehicles with a gasoline engine)
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 work-
shop. 6
N The yellow reserve fuel warning lamp is on while the engine is running.
The fuel level has dropped to the reserve range.
X Refuel at the nearest gas station. ?
N The red coolant warning lamp comes on while the engine is running.
On vehicles without steering wheel buttons, the coolant temperature gauge is at
the start of the bar display
(Y page 178).
On vehicles with steering wheel buttons, the coolant temperature gauge is at
the start of the scale in the instrument cluster ( Y page 40).
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 traffic conditions,
and switch off the engine. Do not continue driving under any circumstances.
X Secure the vehicle to prevent it from rolling away (Y page
138).
X Consult a qualified specialist workshop. Indicator and warning lamps in the instrument cluster
233
On-board computer and displays Z

Warning/
indicator
lamp
N Signal type
Possible causes/consequences and
M Solutions?
N 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 display messages.
X Stop the vehicle immediately, paying attention to road and traffic conditions,
and switch off the engine.
X Secure the vehicle to prevent it from rolling away (Y page 138).
X Exit 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

253).
X If you have to add coolant more frequently, have the engine cooling system
checked.
X Make sure that the air supply to the radiator is not obstructed, by frozen
slush for example.
X Check the coolant temperature:
R using the display in the on-board computer on vehicles without steering
wheel buttons ( Y page

178)
R using the analog display in the instrument cluster on vehicles with steering
wheel buttons ( Y page 40)
X Do not start the engine again until the coolant temperature is below the maxi-
mum value specified below. The engine could otherwise be damaged.
X Drive to the nearest qualified specialist workshop.
Avoid heavy loads on the engine, e.g. driving in mountainous terrain, and
stop-start traffic.
Under normal driving conditions and at the correct coolant level, the coolant
temperature display may rise to the letter H or to the red mark.?
N The red coolant warning lamp comes on while the engine is running. An addi-
tional warning tone sounds.
The coolant temperature has exceeded the maximum value specified below. 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 adequately and could become damaged.
Never drive with an overheated engine. Otherwise, fluids which may have leaked
into the engine compartment could catch fire.
In addition, steam from an overheated engine can cause serious burns, which
can occur just by opening the hood.
There is a risk of injury.
X Observe the display messages.
X Stop the vehicle immediately, paying attention to road and traffic conditions,
and switch off the engine. 234
Indicator and warning lamps in the instrument cluster
On-board computer and displays

Warning/
indicator
lamp
N Signal type
Possible causes/consequences and
M SolutionsX
Secure the vehicle to prevent it from rolling away ( Y page 138).
X Exit 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
253).
X If you have to add coolant more frequently, have the engine cooling system
checked.
X Make sure that the air supply to the radiator is not obstructed, by frozen
slush for example.
X Check the coolant temperature:
R using the display in the on-board computer on vehicles without steering
wheel buttons ( Y page

178)
R using the analog display in the instrument cluster on vehicles with steering
wheel buttons ( Y page 40)
X If the coolant temperature is below the maximum value specified below, you
can continue driving to the nearest qualified specialist workshop.
Avoid heavy loads on the engine, e.g. driving in mountainous terrain, and
stop-start traffic.
Under normal driving conditions and at the correct coolant level, the coolant
temperature display may rise to the letter H or to the red mark.Driving systems
Warning/
indicator
lamp
N Signal type
Possible causes/consequences and
M Solutions·
N 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. ·
N The red distance warning lamp lights up while the vehicle is in motion. An
additional warning tone 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 particular attention to the traffic situation. You may have to brake or take
evasive action.
Further information about the distance warning function can be found under
"COLLISION PREVENTION ASSIST"
(Y page 149). Indicator and warning lamps in the instrument cluster
235
On-board computer and displays Z

X
Hold support strut ? and lift the hood
slightly.
X Guide support strut ? towards retainer =
and apply slight pressure to make it engage.
X Lower the hood and allow it to fall with
momentum from a height of approximately
1 ft (30 cm
).
The hood locks audibly.
X Check that the hood is correctly locked.
If the hood can be raised slightly, it is not
properly engaged. If the hood is not cor-
rectly engaged, open the hood again. Let
the hood fall with a little more momentum. Overview of the engine compart-
ment
Engine compartment (example)
:
Engine oil filler neck cap (Y page
252)
; Brake fluid reservoir cap (Y page
255)
= Coolant expansion tank cap ( Y page
253)
? Washer fluid reservoir cap (Y page
256)
Regularly check the fluid level and the assem-
bly for leaks. If you detect fluid loss, e.g. oil
stains on the vehicle parking space, consult a
qualified specialist workshop immediately. Engine oil
General notes !
Engine oil gets dirty in the course of opera-
tion and its quality and volume are gradually
diminished. Regularly check the oil level,
and top up or have it replaced as needed.
Observe the information on approved engine
oils and oil consumption under "Service prod-
ucts and capacities" ( Y page

308).You can check the oil level in the engine:
R with the oil dipstick
Checking the oil level using the oil dip-
stick G
WARNING
Opening the hood when the engine is over-
heated or when there is a fire in the engine
compartment could expose you to hot gases
or other service products. There is a risk of
injury.
Let an overheated engine cool down before
opening the hood. If there is a fire in the
engine compartment, keep the hood closed
and contact the fire department. G
WARNING
Certain components in the engine compart-
ment, such as the engine, radiator and parts
of the exhaust system, can become very
hot. Working in the engine compartment
poses a risk of injury.
Where possible, let the engine cool down
and touch only the components described in
the following. Oil dipstick and engine oil filler neck
Only check the oil level when the engine is at
normal operating temperature. X Stop your vehicle as far away from traffic as
possible on level ground.
X Secure the vehicle to prevent it from rolling
away.
X Switch off the engine.
X Wait for five minutes.252
Engine compartment
Maintenance and care

Comply with instructions on the use, storage
and disposal of service products on the
labels of the respective original containers.
Always store service products sealed in their
original containers. Always keep service
products out of the reach of children. G
WARNING
Opening the hood when the engine is over-
heated or when there is a fire in the engine
compartment could expose you to hot gases
or other service products. There is a risk of
injury.
Let an overheated engine cool down before
opening the hood. If there is a fire in the
engine compartment, keep the hood closed
and contact the fire department. G
WARNING
Certain components in the engine compart-
ment, such as the engine, radiator and parts
of the exhaust system, can become very
hot. Working in the engine compartment
poses a risk of injury.
Where possible, let the engine cool down
and touch only the components described in
the following.
Coolant contains glycol and is therefore poi-
sonous. Also observe the safety notes under
"Service products and capacities"
(Y page
305). G
WARNING
The cooling system is pressurized, particu-
larly when the motor is warm. If you open
the cap, you could be scalded if hot coolant
sprays out. There is a risk of injury.
Let the engine cool down before you open
the cap. Wear protective gloves and protec-
tive eyewear when opening. Open the cap
slowly to release pressure.
Only check the coolant level and/or fill the
coolant if the vehicle is on a level surface and
the engine has cooled down. The coolant tem-
perature must be below

122 ‡ (50 †). The
coolant temperature gauge must no longer reach the first line after the letter
C on the
scale and/or the bar display.
! Check the engine cooling and heating sys-
tem regularly for leaks.
If a large quantity of coolant is lost, have the
cause traced and rectified at a qualified spe-
cialist workshop. 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.
! Take care not to spill any coolant on pain-
ted surfaces. You could otherwise damage
the paintwork. Example: cap and coolant expansion tank
Checking the coolant level
X Stop your vehicle as far away from traffic as
possible on level ground.
X Switch off the engine.
X Secure the vehicle to prevent it from rolling
away.
X Open the hood (Y page
251).
X Allow the engine to cool down.
X Unscrew cap : slowly about half a turn
counter-clockwise and allow excess pres-
sure to escape. 254
Engine compartment
Maintenance and care

X
Turn cap : further and remove it from cool-
ant expansion tank ;.
X Check the coolant level.
If the coolant is up to marker bar =
in the
filler neck when cold, there is a sufficient
amount of coolant in coolant expansion
tank ;.
If the coolant is approximately 0.59 in
(1.5 cm) above marker bar = in the filler
neck when warm, there is a sufficient
amount of coolant in coolant expansion
tank ;.
Adding coolant X If the coolant drops under marker bar = in
the filler neck, add coolant.
Observe the information on the correct cool-
ant mixture ratio and the required water
quality under "Service products and capaci-
ties" ( Y page

310). To prevent damage to
the engine cooling system, use only
approved corrosion inhibitor/antifreeze that
complies with the Mercedes-Benz Specifica-
tions for Service Products.
X Replace cap : and tighten in a clockwise
direction.
X Start the engine.
X Set the temperature in the vehicle interior to
the maximum output on the air-conditioning
system control panel.
X After approximately five minutes, switch off
the engine again and allow it to cool down.
X Check the coolant level again and add cool-
ant if necessary.
X Close the hood. Brake fluid
G
WARNING
Service products may be poisonous and haz-
ardous to health. There is a risk of injury.
Comply with instructions on the use, storage
and disposal of service products on the
labels of the respective original containers.
Always store service products sealed in their
original containers. Always keep service
products out of the reach of children. G
WARNING
Opening the hood when the engine is over-
heated or when there is a fire in the engine
compartment could expose you to hot gases
or other service products. There is a risk of
injury.
Let an overheated engine cool down before
opening the hood. If there is a fire in the
engine compartment, keep the hood closed
and contact the fire department. G
WARNING
Certain components in the engine compart-
ment, such as the engine, radiator and parts
of the exhaust system, can become very
hot. Working in the engine compartment
poses a risk of injury.
Where possible, let the engine cool down
and touch only the components described in
the following.
Brake fluid is hazardous to health. Also
observe the safety notes under "Service prod-
ucts and capacities"
(Y page 305). G
WARNING
The brake fluid constantly absorbs moisture
from the air. This lowers the boiling point of
the brake fluid. If the boiling point of the
brake fluid is too low, vapor pockets may
form in the brake system when the brakes
are applied hard. This would impair braking
efficiency. There is a risk of an accident.
You should have the brake fluid renewed at
the specified intervals.
! If the brake fluid level in the brake fluid
reservoir has fallen to the MIN mark or
below, check the brake system immediately
for leaks. Also check the thickness of the
brake linings. Visit a qualified specialist
workshop immediately.
Do not add brake fluid. This does not cor-
rect the malfunction.
! Brake fluid corrodes paint, plastic and rub-
ber. If paint, plastic or rubber has come into
contact with brake fluid, rinse with water
immediately. Engine compartment
255
Maintenance and care Z

the coolant system and reduce the engine's
service life.
The coolant is a mixture of water and anti-
freeze and corrosion inhibitor. It performs the
following tasks:
R Anti-corrosion protection
R Antifreeze protection
R Raises the boiling point
When the vehicle is first delivered, it is filled
with a coolant mixture that ensures adequate
antifreeze/corrosion protection. Coolant must
remain in the engine cooling system all year
round to ensure anti-corrosion protection and
a higher boiling point, even in countries with
high outside temperatures.
Check the antifreeze/corrosion inhibitor con-
centration in the coolant every six months.
The percentage of corrosion inhibitor/anti-
freeze additive in the engine cooling system
should:
R be at least
50%. This way, the engine cooling
system is protected 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.
Mercedes-Benz recommends an antifreeze and
corrosion inhibitor that meets the require-
ments in the Mercedes-Benz Specifications for
Service Products Sheet Number 325.
More information can be obtained at any quali-
fied specialist workshop.
Operating fluid: coolant Product name/number
Zerex G40-91, The Valvoline Company
MB Sheet No. 325.5
Maintenance interval
Have the coolant replaced at specified inter-
vals by a qualified specialist workshop.
Capacities Engine cooling system
Coolant
Approx. 11 US qt
(10.4 l
) Climate control system refrigerants
Important safety notes The climate control system of your vehicle is
filled with the refrigerant R ‑134a.
The warning label for the refrigerant being
used can be found on the radiator cross mem-
ber.
! Only the refrigerant R‑134a and the PAG
oil approved by Mercedes-Benz may be
used. The approved PAG oil may not be
mixed with any other PAG oil that is not
approved for R-134a refrigerant. Otherwise,
the climate control system may be dam-
aged.
Maintenance work such as adding refrigerant
or replacing components may only be carried
out by a qualified specialist workshop. All
applicable regulations thereto and the SAE
standard J639 must be adhered to.
All work on the climate control system should
always be carried out at qualified specialist
workshop.
Refrigerant warning label Refrigerant warning label (example)
: Warning symbols
; Refrigerant capacity
= Applicable standards
? Part number PAG oil
A Type of refrigerant
The symbol : refers to:
R possible dangers
R the implementation of maintenance work at
a qualified specialist workshop Service products and capacities
311
Technical data Z