check engine MERCEDES-BENZ GLS 2018 Owner's Guide

Display messages
Possible causes/consequences and P Solutions
The yellow $ warning lamp lights up and th e red I (US A only)
or $ (Canada only) indicator lamp flashes .
It is no t possibl e to apply th e electric parking brak e manually.X
Shift th e transmission to position ] .X
Visit a qualified specialist workshop .
' (US A only)
M (Canada only)
Check Brake Fluid
Level There is no t enough brak e flui d in th e brak e flui d reservoir . In addition ,
th e ' (US A only) or M (Canada only) warning lamp lights up in
th e instrumen t cluste r and a warning tone sounds.
G WARNIN G
The braking effec t may be impaired.
There is a ris k of an accident.X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions. Do no t continu e drivin g
under any circumstances. X
Secur e th e vehicl e against rollin g away ( Y
page 161).X
Consult a qualified specialist workshop .X
Do no t add brak e fluid . This does no t correc t th e malfunction .
& Check Brake Pad Wea r The brak e pads/linings hav e reached their wear limit.
US A only: th e ' red brak e system warning lamp is lit while th e
engin e is running. X
Visit a qualified specialist workshop .
S Inoperative On e or mor e main features of th e mbrace system are malfunctioning .X
Visit a qualified specialist workshop .
Active Brake Assist
Functions Currently
Limite d See Opera‐
tor's Manual Active Brake Assis t wit h cross-traffic function is temporarily inopera-
tive.
Possibl e causes are: R
The radar sensor system is temporarily inoperative, e.g. due to
electromagneti c radiation emitted by nearby TV or radi o station s or
other source s of electromagneti c radiation .R
The system is outside th e operating temperature range.R
The on-boar d voltag e is to o low.
Whe n th e causes state d abov e no longer apply, th e display message
disappears.
Active Brake Assis t wit h cross-traffic function or PRE ‑ S AF E ®
PLU S is
functional again .
If th e display message does no t disappear :X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 161).X
Restart th e engine.254
Display messages
On-board computer and displays

Warning/
indicator
lamp Q Signal type
Possible causes/consequences and P Solutions
I$
Q I (USA only), $ (Canada only): the red indicator lamp for the electric
parking brake flashes or is lit and/or the yellow warning lamp for the electric
parking brake is lit. X
Observe the additional display messages in the multifunction display.
u
Q The red restraint system warning lamp is lit while the engine is running.
The restraint system is malfunctioning.
G WARNING
The air bags or Emergency Tensioning Devices may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
There is an increased risk of injury. X
Observe the additional display messages in the multifunction display. X
Drive on carefully. X
Contact a qualified specialist workshop and have the restraint system checked.
For further information about the restraint system, see ( Y
page 44).Warning and indicator lamps in the instrument cluster 287
On-board computer and displays Z

X
Make sure that the windshield wipers are
turned off. X
Pull release lever C on the hood.
The hood is released.
X
Reach into the gap, pull hood catch handle D
up and lift the hood.
If you lift the hood by approximately 15 in
(40 cm), the hood is opened and held open
automatically by the gas-filled strut.
Closing the hood X
Lower the hood and let it fall from a height of
approximately 8 in (20 cm). X
Check that the hood has engaged properly.
If the hood can be raised slightly, it is not
properly engaged. Open it again and close it
with a little more force.
Radiator
Vehicles with a diesel engine: do not cover
the radiator. such as with a thermal mat or
insect protection cover. Otherwise, the values of
the European on-board diagnostics may be
affected. Some of these readings are required
by law and must be accurate at all times. Engine oil
Important safety notes
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.
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
If engine oil comes into contact with hot com-
ponents in the engine compartment, it may
ignite. There is a risk of fire and injury.
Make sure that engine oil is not spilled next to
the filler neck. Let the engine cool down and
thoroughly clean the engine oil off the com-
ponents before starting the engine.
General notes Depending on your driving style, the vehicle
consumes up to 0.9 US qt (0.8 liters) of oil per
600 miles (1,000 km). The oil consumption may
be higher than this when the vehicle is new or if
you frequently drive at high engine speeds.
Depending on the engine, the oil dipstick may be
in a different location.326
Engine compartment
Maintenance and care

When checking the oil level: R
park the vehicle on a level surface. R
the engine should be switched off for approx-
imately five minutes if the engine is at normal
operating temperature. R
if the engine is not at normal operating tem-
perature, e.g. if the engine was only started
briefly, wait about 30 minutes before carrying
out the measurement.
Checking the oil level using the oil dip-
stick
Example: vehicles with a gasoline engine
Example: vehicles with a diesel engine X
Pull oil dipstick C out of the dipstick tube.X
Wipe off oil dipstick C .X
Slowly slide oil dipstick C into the guide tube
to the stop, and take it out again.
If the level is between MIN mark

Further information on engine oil ( Y
page 389).
Additional service products
Important safety notes
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.
G WARNING
The cooling system is pressurized, particularly
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 gloves and eye protection. Slowly
open the cap to relieve pressure.
The coolant level may only be checked and cool-
ant refilled when the engine and engine cooling
system have cooled down.
G WARNING
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. Checking coolant level X
Park the vehicle on a level surface.
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 H in the igni-
tion lock ( Y
page 140).
On vehicles with KEYLESS-GO, press the
Start/Stop button twice ( Y
page 142).X
Check the coolant temperature gauge in the
multifunction display.
The coolant temperature must be below
158 ‡ (70 †). X
Turn the SmartKey to position in the ignition
lock

A qualified specialist workshop will reset the
ASSYST service interval display after the service
work has been carried out. You can also obtain
further information on maintenance work, for
example.
Special service requirements The specified maintenance interval takes only
the normal operation of the vehicle into
account. Under increased load on the vehicle,
maintenance work must be carried out more
frequently, for example: R
Regular city driving with frequent intermedi-
ate stops R
If the vehicle is primarily used to travel short
distances R
Use in mountainous terrain or on poor road
surfaces R
If the engine is often left idling for long periods
Under these or similar conditions, have, for
example, the air filter, engine oil and oil filter
replaced or changed more frequently. Under
arduous operating conditions, the tires must be
checked more often. Further information can be
obtained at a qualified specialist workshop.
Driving abroad An extensive Mercedes-Benz Service network is
also available in other countries. You can obtain
further information from any authorized
Mercedes-Benz Center.
Care
General notes
H Environmental note
Dispose of empty packaging and cleaning
cloths in an environmentally responsible man-
ner.
! When cleaning your car, do not use: R
dry, coarse or hard cloths R
abrasive cleaning agents R
solvents R
cleaning agents containing solvents
Do not scrub.
Do not touch the surfaces and films with hard
objects, e.g. rings or ice scrapers. Otherwise, you may scratch or damage the surfaces and
films.
! Do not park your vehicle for a long period of
time directly after cleaning, particularly after
cleaning the wheel rim with wheel cleaner.
Wheel cleaner can lead to the increased cor-
rosion of the brake discs and pads. Therefore,
drive for a few minutes after cleaning. By
heating up the brakes, the brake discs and
pads dry. The vehicle can then be parked for a
long period of time.
Regular care of your vehicle is a condition for
retaining the quality in the long term.
Use care products and cleaning agents recom-
mended and approved by Mercedes-Benz.
Washing the vehicle and cleaning the
paintwork
Automatic car wash
G WARNING
Braking efficiency is reduced after washing
the vehicle. There is a risk of an accident.
After the vehicle has been washed, brake
carefully while paying attention to the traffic
conditions until full braking power is restored.
! Before driving into an automatic car wash,
make sure that it is suitable for the dimen-
sions of the vehicle. In particular, make sure
that: R
there is enough ground clearance between
the vehicle underbody and the guide rails of
the automatic car wash. R
the clearance width of the automatic car
wash is sufficient, particularly the width of
the guide rails. R
you enter the automatic car wash straight
and in the center of the guide rails in order
to avoid damaging the tires or wheel rims.
Fold in the exterior mirrors before the vehicle
is washed. The exterior mirrors could other-
wise be damaged.
! When Distance Pilot DISTRONIC or the
HOLD function is activated, the vehicle
brakes automatically in certain situations.330
Care
Maintenance and care

Charging the 12 V battery
G WARNING
During charging and jump-starting, explosive
gases can escape from the battery. There is a
risk of an explosion.
Particularly avoid fire, open flames, creating
sparks and smoking. Ensure there is sufficient
ventilation while charging and jump-starting.
Do not lean over a battery.
G WARNING
Battery acid is caustic. There is a risk of injury.
Avoid contact with skin, eyes or clothing. Do
not inhale any battery gases. Do not lean over
the battery. Keep children away from batter-
ies. Wash away battery acid immediately with
plenty of clean water and seek medical atten-
tion.
G WARNING
A discharged battery can freeze at tempera-
tures below freezing point. When jump-start-
ing the vehicle or charging the battery, gases
can escape from the battery. There is a risk of
an explosion.
Allow the frozen battery to thaw out before
charging it or jump-starting.
! Only use battery chargers with a maximum
charging voltage of 14.8 V. ! Only charge the battery using the jump-
starting connection point.
The jump-starting connection point is in the
engine compartment ( Y
page 346).X
Open the hood. X
Connect the battery charger to the positive
terminal and ground point in the same order
as when connecting the donor battery in the
jump-starting procedure ( Y
page 346).
Keep away from fire and open flames. Do not
lean over a battery. Never charge the battery if it
is still installed in the vehicle, unless you use a
battery charger which has been tested and
approved by Mercedes-Benz. A battery charger
unit specially adapted for Mercedes-Benz vehi-
cles and tested and approved by Mercedes-
Benz is available as an accessory. It permits the
charging of the battery in its installed position.
Contact an authorized Mercedes-Benz Center
for further information and availabilit y. Read t he
batt ery charger's operating instructions before
charging the battery.
If, at low temperatures, the indicator lamps/
warning lamps in the instrument cluster do not
light up, it is highly likely that the discharged
battery has frozen. In this case you may neither
jump-start the vehicle nor charge the battery.
The service life of a thawed-out battery may be
shorter. The starting characteristics can be
impaired, particularly at low temperatures. Have
the thawed-out battery checked at a qualified
specialist workshop.
Jump-starting
For the jump-starting procedure, use only the jump-starting connection point in the engine com-
partment, consisting of a positive terminal and a ground point.
G WARNING
Battery acid is caustic. There is a risk of injury.
Avoid contact with skin, eyes or clothing. Do not inhale any battery gases. Do not lean over the
battery. Keep children away from batteries. Wash away battery acid immediately with plenty of
clean water and seek medical attention.
G WARNING
During charging and jump-starting, explosive gases can escape from the battery. There is a risk
of an explosion.346
Jump-starting
Breakdown assistance

Particularly avoid fire, open flames, creating sparks and smoking. Ensure there is sufficient ven-
tilation while charging and jump-starting. Do not lean over a battery.
G WARNING
During the charging process, a battery produces hydrogen gas. If a short circuit occurs or sparks
are created, the hydrogen gas can ignite. There is a risk of an explosion. R
Make sure that the positive terminal of a connected battery does not come into contact with
vehicle parts. R
Never place metal objects or tools on a battery. R
It is important that you observe the described order of the battery terminals when connecting
and disconnecting a battery. R
When jump-starting, make sure that the battery poles with identical polarity are connected. R
It is particularly important to observe the described order when connecting and disconnecting
the jumper cables. R
Never connect or disconnect the battery terminals while the engine is running.
G WARNING
A discharged battery can freeze at temperatures below freezing point. When jump-starting the
vehicle or charging the battery, gases can escape from the battery. There is a risk of an explosion.
Allow the frozen battery to thaw out before charging it or jump-starting.
! Vehicles with a gasoline engine: avoid repeated and lengthy starting attempts. Otherwise, the
catalytic converter could be damaged by non-combusted fuel.
If the indicator/warning lamps do not light up at low temperatures, it is very likely that the dis-
charged battery has frozen. In this case you may neither jump-start the vehicle nor charge the
battery. The service life of a thawed-out battery may be shorter. The starting characteristics can be
impaired, particularly at low temperatures. Have the thawed-out battery checked at a qualified
specialist workshop.
Do not start the vehicle using a rapid charging device. If your vehicle's battery is discharged, the
engine can be jump-started from another vehicle or from a donor battery using jumper cables.
Observe the following points: R
The battery is not accessible in all vehicles. If the other vehicle's battery is not accessible, jump-
start the vehicle using a donor battery or a jump-starting device. R
Vehicles with a gasoline engine: only jump-start the vehicle when the engine and exhaust
system are cold. R
Do not start the engine if the battery is frozen. Let the battery thaw first. R
Only jump-start from batteries with a 12 V voltage rating. R
Only use jumper cables which have a sufficient cross-section and insulated terminal clamps. R
If the battery is fully discharged, leave the battery that is being used to jump-start connected for
a few minutes before attempting to start. This charges the battery slightly. R
Make sure that the two vehicles do not touch. Jump-starting 347
Breakdown assistance Z

shop, e.g. at an authorized Mercedes-Benz Cen-
ter.
X
Open the front-passenger door. X
To open: pull cover C outwards in the direc-
tion of the arrow and remove it. X
To close: clip in cover C on the front of the
dashboard. X
Fold cover C inwards until it engages.
Fuse box in the engine compartment
G WARNING
When the hood is open and the windshield
wipers are set in motion, you can be injured by
the wiper linkage. There is a risk of injury.
Always switch off the windshield wipers and
the ignition before opening the hood.
X
Open the hood ( Y
page 325).X
Use a dry cloth to remove any moisture from
the fuse box. X
To open: open clamps D .X
Fold up cover C in the direction of the arrow
and remove it. X
To close: check whether the seal is seated
correctly in cover C .X
Insert cover C at the side of the fuse box into
the retainers. X
Fold down cover C and close clamps D .X
Close the hood.
Fuse box under the rear bench seat X
Fold the left-hand rear bench seat forward
( Y
page 303). X
To open: reach into recesses D on each side
of fuse box cover C .X
Fold cover C up in the direction of the arrow
and remove it from the fuse box.
i The fuse allocation chart is located in a
recess at the side of the fuse box. X
To close: place cover C on the fuse box.X
Press cover C down until you feel the clamps
engage. X
Fold back the left-hand rear bench seat
( Y
page 303). Fuses 353
Breakdown assistance Z

be required earlier. Do not change the direction
of wheel rotation.
Clean the contact surfaces of the wheel and the
brake disc thoroughly every time a wheel is rota-
ted. Check the tire pressure and, if necessary,
restart the tire pressure loss warning system or
the tire pressure monitor ( Y
page 361).
Direction of rotation Tires with a specified direction of rotation have
additional benefits, e.g. if there is a risk of hydro-
planing. These advantages can only be gained if
the tires are installed corresponding to the
direction of rotation.
An arrow on the sidewall of the tire indicates its
correct direction of rotation.
Storing wheels Store wheels that are not being used in a cool,
dry and preferably dark place. Protect the tires
from oil, grease, gasoline and diesel.
Mounting a wheel
Preparing the vehicle X
Vehicle with emergency spare wheel:
when mounting the emergency spare wheel in
the event of a flat tire, follow the additional
notes on vehicle preparation under "Flat tire"
( Y
page 339). X
Stop the vehicle on solid, non-slippery and
level ground. X
Apply the electric parking brake manually. X
Bring the front wheels into the straight-ahead
position. X
Vehicles with automatic transmission:
shift the transmission to position ] .X
Vehicles with the AIRMATIC package:
make sure that the normal vehicle level is
selected ( Y
page 190).X
Vehicles with the Off-Road Engineering
package: make sure that the normal level is
selected ( Y
page 184).X
Switch off the engine. X
Vehicles without KEYLESS-GO: remove the
SmartKey from the ignition lock. X
Vehicles with KEYLESS-GO: open the driv-
er's door.
The vehicle electronics are now in position