
ProblemPossible causes/consequences andMSolutions
?
The red coolant
warning lamp is lit
while the engine
is running.The coolant temperature is too high.
XStop the vehicle as soon as possible, paying attention to road and
traffic conditions.
XConsult a qualified specialist workshop.
?The red coolant
warning lamp is lit
while the engine
is running.The coolant temperature is too high.
If the vehicle is stopped after being subjected to extreme loads, the
coolant warning lamp may come on when the ignition is switched on
or the engine is restarted. Such loads can be, for example, driving in
mountainous terrain or driving with a trailer.
XRun the engine for approximately 1 minute at idling speed.
XConsult a qualified specialist workshop if the display message con-
tinues to be shown.
7
|The yellow
reserve fuel warn-
ing lamp is on. At
the same time,
0
appears in the
fuel tank content
display while the
engine is running,
although there is
fuel in the fuel
tank.
The fuel filler cap is not closed.
XClose the fuel filler cap.
You will hear a click when the fuel filler cap is closed fully.
XIf the malfunction continues to be displayed, have it rectified imme-
diately at a qualified specialist workshop.
;
The yellow Check
Engine indicator
lamp is lit up or
flashes while the
engine is running.You have used up all fuel in the tank.
The engine is running in emergency mode.
XRefuel at the nearest gas station (Ypage 124).
XBleed the fuel system (Ypage 120).
XStart the engine three to four times in succession after refueling.
Emergency running mode will be canceled. The vehicle does not
need to be checked.
;The yellow Check
Engine indicator
lamp is lit up or
flashes while the
engine is running.The injection control is malfunctioning.
The engine is running in emergency mode.
Engine power output may be reduced.
XHave the vehicle checked at a qualified specialist workshop as soon
as possible.
In some states it is legally prescribed that after the Check Engine
indicator lamp lights up you must contact a qualified specialist work-
shop immediately. Observe the legal requirements.
196Indicator and warning lamps in the instrument cluster
On-board computer and displays

ProblemPossible causes/consequences andMSolutions
;
The yellow Check
Engine indicator
lamp is lit while
the engine is run-
ning.The exhaust gas aftertreatment is malfunctioning or an emission rel-
evant malfunction has occurred. This malfunction or defect can dam-
age the exhaust gas aftertreatment.
After the first message and under normal operating conditions, you
can drive on for up to approximately 500 mi (800 km). Then a warning
tone sequence sounds and the engine can only be started another 16
times.
XObserve the messages in the display.
XHave the exhaust gas aftertreatment checked immediately at a
qualified specialist workshop.
In some states it is legally prescribed that after the Check Engine
indicator lamp lights up you must contact a qualified specialist work-
shop immediately. Observe the legal requirements.
% If you turn the
SmartKey to posi-
tion2in the igni-
tion lock, the yel-
low preglow indi-
cator lamp
remains lit for
approximately
1 minute. Or the
yellow preglow
indicator lamp
lights up for
approximately
1 minute while
the engine is run-
ning.At extremely low temperatures, the engine may not start.
There is a malfunction in the preglow system.
XHave any malfunction rectified at a qualified specialist workshop.
È The yellow air fil-
ter indicator lamp
is lit while the
engine is running.The service limit for the air filter has been reached. The air filter is dirty.
XHave the air filter element replaced as soon as possible at a quali-
fied specialist workshop.
hThe yellow tire
pressure monitor
warning lamp
comes on.GWARNING
The tire pressure monitor indicates a rapid or severe loss of pressure
in at least one tire.
XStop the vehicle without making any extreme steering maneuvers or
braking suddenly. Pay attention to the traffic conditions while doing
so.
XCheck the tires and correct the tire pressure. If a tire continues to
lose pressure, it must be replaced. Replace damaged tires imme-
diately.
The warning light will go out after the flat tire has been rectified and
you have been driving for a few minutes.
XVehicles with steering wheel buttons: also observe the messages in the display (Ypage 173).
Indicator and warning lamps in the instrument cluster197
On-board computer and displays
Z

ProblemPossible causes/consequences andMSolutions
h
US vehicles only:
The yellow tire
pressure monitor
warning lamp
flashes for
60 seconds and
then remains lit.The tire pressure monitor has malfunctioned.
XHave the tire pressure monitor and the wheels checked at a quali-
fied specialist workshop.
:
The yellow water
separator indica-
tor lamp is lit
when the ignition
is switched on.The water that has collected in the water separator of the fuel filter has
reached the maximum level.
XDrain the water separator (Ypage 220).
m
The yellow water
separator indica-
tor lamp is lit
when the ignition
is switched on.The fuel filter is dirty.
XHave the fuel filter element replaced as soon as possible at a quali-
fied specialist workshop.
¦The yellow
washer fluid level
indicator lamp for
the windshield
washer/head-
lamp cleaning
system is lit after
the engine is star-
ted or while the
vehicle is in
motion.The water level is too low.
XAdd washer fluid (Ypage 220).
7The red seat belt
warning lamp
lights up continu-
ously or flashes. A
warning tone may
also sound.The warning lamp is to remind you to fasten your seat belt.
XFasten seat belt (Ypage 43).
bWhen the Smart-
Key is turned to
position 2in the
ignition lock, the
yellow bulb warn-
ing lamp lights up.One of the exterior lighting bulbs is faulty, with the exception of the
perimeter lamps and the trailer lighting.
iDepending on the equipment, the bulb failure indicator can fail for
all lamps with the exception of the turn signal lamps.
XReplace the faulty bulb as soon as possible (Ypage 87).
1 The yellow "door
open" indicator
lamp is lit while
driving.The vehicle is moving without all doors or the hood being closed.
XClose the doors or hood.
198Indicator and warning lamps in the instrument cluster
On-board computer and displays

Checking the brake fluid level
XStop your vehicle as far away from traffic as
possible on level ground.
XSwitch off the engine.
XSecure the vehicle to prevent it from rolling
away.
XOpen the hood (Ypage 214).
XCheck the brake fluid level.
The brake fluid level is correct if the level is
between the MIN mark and MAX mark on
brake fluid reservoir:.
XClose the hood.
!If the brake fluid level in the brake fluid res-
ervoir 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 correct
the malfunction.
Washer fluid
GWARNING
Windshield washer concentrate could ignite if it comes into contact with hot engine compo-
nents or the exhaust system. There is a risk of
fire and injury.
Make sure that no windshield washer con-
centrate is spilled next to the filler neck.
!Only use washer fluid that is suitable for
plastic lamp lenses, e.g. MB SummerFit or MB WinterFit. Unsuitable washer fluid could dam-
age the plastic lenses of the headlamps.
Example: washer fluid reservoir
Add windshield washer concentrate to the
washer fluid all year round. Observe the infor-
mation on washer fluid in the "Technical data"
section (
Ypage 281).
Adding washer fluid
XMix the washer fluid to the appropriate mixing ratio in a container beforehand.
XOpen the hood (Ypage 214).
XPull cap :on the washer fluid reservoir
upwards at the tab.
XAdd the premixed washer fluid.
XPress cap :onto the filler neck until it
engages audibly.
XClose the hood.
Fuel system
Draining the fuel filter
GWARNING
Fuel is highly flammable. Improper handling of
fuel creates a risk of fire and explosion.
Avoid fire, open flames, smoking and creating
sparks under all circumstances. Switch off the
ignition and auxiliary heating before carrying
out work to the fuel system. Always wear pro-
tective gloves.
HEnvironmental note
Dispose of the water-fuel mixture in an envi-
ronmentally responsible manner.
!When the :indicator lamp lights up,
drain the fuel filter with water separator
immediately. Otherwise, the engine may be
damaged.
220Engine compartment
Maintenance and care

flated tire causes the tire to overheat and canlead to tire failure. Underinflation also
reduces fuel efficiency and tire tread life, and
may affect the vehicle's handling and stop-
ping ability.
Please note that the TPMS is not a substitute
for proper tire maintenance, and it is the driv-
er's responsibility to maintain correct tire
pressure, even if underinflation has not
reached the level to trigger illumination of the
TPMS low tire pressure telltale.
USA only:
Your vehicle has also been equipped with a
TPMS malfunction indicator to indicate if the
system is not operating properly. The TPMS
malfunction indicator is combined with the
low tire pressure telltale. When the system
detects a malfunction, the warning lamp will
flash for approximately a minute and then
remain continuously illuminated. This
sequence will be repeated every time the vehi-
cle is started as long as the malfunction
exists.
When the malfunction indicator is illuminated,
the system may not be able to detect or signal
low tire pressure as intended. TPMS malfunc-
tions may occur for a variety of reasons,
including the mounting of incompatible
replacement or alternate tires or wheels on
the vehicle that prevent the TPMS from func-
tioning properly. Always check the TPMS mal-
function telltale after replacing one or more
tires or wheels on your vehicle to ensure that
the replacement or alternate tires and wheels
allow the TPMS to continue to function prop-
erly.
Vehicles with a tire pressure monitor are equip-
ped with sensors in the wheels that monitor the
tire pressure of all four tires. The tire pressure
monitor monitors the pressure in all four tires;
you set this pressure when you activate the tire pressure monitor. The tire pressure monitor
warns you when the pressure drops in one or
more of the ti
res. The tire pressure monitor only
functions if the corresponding sensors are
installed on all wheels. You should always adjust the tire pressure
according to the vehicle load. Restart the tire
pressure monitor if you change the tire pres-
sure.
The tire pressure monitor does not warn you if a
tire pressure is incorrect. Observe the notes on the recommended tire pressure (
Ypage 246).
The tire pressure monitor is not able to warn you
of a sudden loss of pressure, e.g. following pen- etration by a foreign object. In this event, brake
the vehicle until it comes to a standstill. Do not
carry out any sudden steering maneuvers.
The tire pressure monitor has a yellow h
warning lamp in the instrument cluster for indi-
cating pressure loss/malfunctions (USA) or
pressure loss (Canada). Depending on how the
warning lamp flashes or lights up, an underin-
flated tire or a malfunction in the tire pressure
monitor is displayed:
Rif the h warning lamp is lit continuously,
the tire pressure on one or more tires is sig-
nificantly too low. The tire pressure monitor is
not malfunctioning.
RUSA only: if the hwarning lamp flashes for
60 seconds and then remains lit constantly,
the tire pressure monitor is malfunctioning.
Only vehicles with steering wheel buttons: the
on-board computer displays information on tire
pressure. After a few minutes of driving, the cur-
rent tire pressure of each tire is shown in the on-
board computer.
USA only: if the tire pressure monitor is mal-
functioning, it may be more than 10 minutes
before the malfunction is shown. The htire
pressure warning lamp flashes for 60 seconds
and then remains lit. When the malfunction has been rectified, the htire pressure warning
lamp goes ou
t after a few minutes of driving.
The tire pressure values indicated by the on-
board computer may differ from those meas-
ured at a gas station with a pressure gage. The
tire pressures shown by the on-board computer
refer to those measured at sea level. At high
altitudes, the tire pressure values indicated by a pressure gage are higher than those shown by
the on-board computer. In this case, do not
reduce the tire pressures.
If radio transmitting equipment (e.g. wireless
headphones, two-way radios) is operated inside
the vehicle or in the vicinity of the vehicle, this
can interfere with the operation of the tire pres-
sure monitor.
250Tire pressure
Wheels and tires