check engine MERCEDES-BENZ GLS SUV 2019 Workshop Manual

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 protective gloves and protective
eyewear when opening. Open the cap slowly
to release pressure.
The coolant level may only be checked and cool- ant refilled when the engine and engine coolingsystem have cooled down. G
WARNING
Windshield washer concentrate is highly flam- mable. If windshield washer concentrate getsonto hot components of the engine or the
exhaust system, it can ignite. There is a risk of
fire and injury.
Make sure that windshield washer concen-
trate is not spilled in the vicinity of 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 0048in 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 0092(Ypage 140).
X On vehicles with KEYLESS-GO, press the
Start/Stop button (Y page 142).
X Press the Start/Stop button (Y page 142).
X Slowly turn cap 0043half a turn counter-clock-
wise and allow excess pressure to escape.
X Turn cap 0043further 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.
If the coolant level is approximately 0.6 in
(1.5 cm) above marker bar 0087in the filler neck
when warm, there is enough coolant in expan- sion tank 0044.
X If necessary, add coolant that has been tested
and approved by Mercedes-Benz.
X Replace cap 0043and turn it clockwise as far as
it will go.
For further information on coolant, see
(Y page 387).
Adding washer fluid to the windshield
washer system Example: washer fluid reservoir
X To open: pull cap0043upwards by the tab.
X Add the premixed washer fluid.
X To close: press cap 0043onto the filler neck
until it engages.
If the washer fluid level drops below the recom- mended minimum of 1 liter, a message appears in the multifunction display prompting you to
add washer fluid (Y page 273).324
Engine compartmentMaintenance and care

Further information on windshield washer fluid
(Y page 388). ASSYST PLUS
Service message
i If the scheduled service intervals are excee-
ded, this may result in damage to the vehicle.
You can obtain up-to-date information concern-
ing the servicing of your vehicle from a qualified specialist workshop, e.g. an authorized
Mercedes-Benz Center or at
http://www.mbusa.com (USA only).
i The ASSYST PLUS service interval display
does not show any information on the engine
oil level. Observe the notes on the engine oil
level (Y page 322).
The multifunction display shows a service mes-
sage for several seconds, e.g.:
R Service A in .. Days Service A in .. Days
R Service A Due
Service A Due
R Service A Exceeded by .. Days
Service A Exceeded by .. Days
Depending on the operating conditions of the
vehicle, the remaining time or distance until the next service due date is displayed.
The letter A
A or B B, possibly in connection with a
number or another letter, shows the type of ser-
vice. A
A stands for a minor service and B
Bfor a
major service.
Further information can be obtained at a quali-
fied specialist workshop.
The ASSYST PLUS service interval display does
not take into account any periods of time during
which the battery is disconnected.
Maintaining the time-dependent service sched-
ule:
X Note down the service due date displayed in
the multifunction display before disconnect-
ing the battery.
or
X After reconnecting the battery, subtract the
battery disconnection periods from the ser-
vice date shown on the display. Hiding a service message
X Press the 0038or0076 button on the steering
wheel. Displaying service messages
X Switch on the ignition.
X Press the 0059or0065 button on the steering
wheel to select the Serv. Serv.menu.
X Press the 0063or0064 button to select the
ASSYST
ASSYST PLUS
PLUSsubmenu and confirm by press-
ing the 0076button.
The service due date appears in the multi-
function display. Information about Service
Resetting the ASSYST PLUS service
interval display !
If the ASSYST PLUS service interval display
has been inadvertently reset, this setting can
be corrected at a qualified specialist work-
shop.
Have service work carried out as described in the Maintenance Booklet. This may otherwise
lead to increased wear and damage to the
major assemblies or the vehicle.
A qualified specialist workshop will reset the
ASSYST PLUS 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. ASSYST PLUS
325Maintenance and care Z

X
Make sure that the vehicle is stationary and
the SmartKey is in position 0048in the ignition
lock.
X Open the camera cover for cleaning via the
multimedia system (see Digital Operator's
Manual).
X To clean the camera: use clean water and a
soft cloth to clean the camera lens 0043.
360° camera: if you drive at speeds above
20 mph (30 km/h) or with the SmartKey in posi- tion 0092or0047 in the ignition lock, the cover of
the 360° camera closes.
Cleaning the exhaust pipe G
WARNING
The exhaust tail pipe and tail pipe trim can
become very hot. If you come into contact
with these parts of the vehicle, you could burn
yourself. There is a risk of burns.
Always be particularly careful and supervise
children closely around the exhaust pipe and
the exhaust pipe trims. Allow these compo-
nents to cool down before touching them.
! Vehicles with black exhaust pipes: black
chromed screens should not be polished with a chrome polish. They will otherwise lose their
black shine. For optimal care, the screens
should be rubbed with a lightly oiled cloth
after every car wash. Commercially available
engine and care oils are suitable for this.
For heavier soiling, you can apply a fine paint- work polish with a microfiber cloth. Remove
the excess polish residue after polishing.
Impurities combined with the effects of road grit
and corrosive environmental factors may cause flash rust to form on the surface. You can
restore the original shine of the exhaust pipe by
cleaning it regularly, especially in winter and
after washing.
X Clean the exhaust pipe with a chrome care
product tested and approved by Mercedes-
Benz.
Cleaning the trailer tow hitch H
Environmental note
Dispose of rags soaked in oil and grease in an environmentally responsible manner. !
Do not clean the ball coupling with a power
washer. Do not use solvents.
! Please note the care instructions in the
trailer coupling manufacturer's operating
instructions. The ball coupling must be cleaned if it becomes
dirty or corroded.
X Remove rust on the ball of the ball coupling,
e.g. with a wire brush.
X Remove dirt with a clean, lint-free cloth or a
brush.
X After cleaning, lightly oil or grease ball cou-
pling 0043.
X Check that the vehicle's trailer tow hitch is
working properly.
i You can also have the maintenance work on
the ball coupling and the trailer tow hitch car-
ried out by a qualified specialist workshop. Interior care
Cleaning the display !
For cleaning, do not use any of the following:
R alcohol-based thinner or gasoline
R abrasive cleaning agents
R commercially-available household cleaning
agents
These may damage the display surface. Do
not put pressure on the display surface when
cleaning. This could lead to irreparable dam-
age to the display. Care
331Maintenance and care Z

X
Stop the vehicle on solid, non-slippery and
level ground, as far away as possible from
traffic.
X Switch on the hazard warning lamps.
X Secure the vehicle against rolling away
(Y page 158).
X If possible, bring the front wheels into the
straight-ahead position.
X Vehicles with the AIRMATIC package:
make sure that the normal vehicle level is
selected (Y page 187).
X Vehicles with the Off-Road Engineering
package:
make sure that the normal level is
selected (Y page 180).
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
0092. This means no SmartKey is in the ignition
lock.
X Vehicles with KEYLESS-GO: remove the
Start/Stop button from the ignition lock
(Y page 140).
X Make sure that the passengers are not endan-
gered as they do so. Make sure that no one is
near the danger area while a wheel is being
changed. Anyone who is not directly assisting in the wheel change should, for example,
stand behind the barrier.
X Get out of the vehicle. Pay attention to traffic
conditions when doing so.
X Close the driver's door.
X Unload heavy luggage.
i Only operate the tire inflation compressor
using a 12 V socket, even if the ignition is
turned off (Y page 307).
An emergency cut-out ensures that the on-
board voltage does not drop too low. If the on-
board voltage is too low, the power to the
sockets is automatically cut. This ensures
that there is sufficient power to start the
engine. MOExtended tires (tires with run-flat
properties)
General notes With MOExtended tires (tires with run flat char-
acteristics), you can continue to drive your vehi- cle even if there is a total loss of pressure in one
or more tires. The affected tire must not show
any clearly visible damage.
You can recognize an MOExtended tire by the
MOExtended marking which appears on the
sidewall of the tire. You will find this marking
next to the tire size designation, the load-bear-
ing capacity and the speed index (Y page 367).
MOExtended tires may only be used in conjunc-
tion with an active tire pressure loss warning
system or with an active tire pressure monitor.
If a pressure loss warning message appears in the multifunction display:
R observe the instructions in the display mes-
sages (Y page 268).
R check the tire for damage
R if driving on, observe the following notes
The driving distance possible in run-flat mode is approximately 50 miles (80 km) when the vehi-
cle is partially laden and approximately 18 miles
(30 km) when the vehicle is fully laden.
In addition to the vehicle load, the driving dis-
tance possible depends upon:
R Vehicle speed
R Road condition
R Outside temperature
The driving distance possible in run-flat mode
may be reduced by extreme driving conditions
or maneuvers, or it can be increased through a
moderate style of driving.
The driving distance possible in run-flat mode is counted from the moment the tire pressure loss warning appears in the multifunction display.
You must not exceed a maximum permissible
speed of 50 mph (80 km/h).
i When replacing one or all tires, please
observe the following specifications for your
vehicle's tires:
R Size
R Type and
R The "MOExtended" mark
If a tire has gone flat and cannot be replaced with an MOExtended tire, a standard tire may 336
Flat tireBreakdown assistance

R
Make sure that the positive terminal of a
connected battery does not come into con-
tact with vehicle parts.
R Never place metal objects or tools on a bat-
tery.
R It is important that you observe the descri-
bed 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 dis-
connecting the jumper cables.
R Never connect or disconnect the battery
terminals while the engine is running. 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. H
Environmental note Batteries contain dangerous
substances. It is against the
law to dispose of them with
the household rubbish. They
must be collected separately
and recycled to protect the
environment. Dispose of batteries in an
environmentally friendly
manner. Take discharged
batteries to a qualified spe-
cialist workshop or a special
collection point for used bat-
teries.
! Have the battery regularly checked at a
qualified specialist workshop.
For more information, please contact a quali- fied specialist workshop. !
Always have work on batteries carried out at
a qualified specialist workshop.
Should it, in exceptional circumstances, be
absolutely necessary to disconnect the 12-
volt battery yourself, please observe the fol-
lowing:
R Secure the vehicle to prevent it from rolling
away.
R Switch off the ignition.
R Disconnect the negative terminal first and
then the positive terminal.
The transmission is locked in position 005D
after disconnecting the battery.
After the work has been done, install the bat-
tery and replace the cover of the positive ter- minal clamp firmly.
Comply with safety precautions and take pro-
tective measures when handling batteries. Risk of explosion.
Fire, open flames and smoking are
prohibited when handling the bat-
tery. Avoid creating sparks.
Battery acid is caustic. Avoid contact
with skin, eyes or clothing.
Wear suitable protective clothing,
especially gloves, apron and face-
guard.
Rinse any acid spills immediately
with clear water. Contact a physician if necessary. Wear eye protection.
Keep children away.
Observe this Operator's Manual.
For safety reasons, Mercedes-Benz recom-
mends that you only use batteries which have
been tested and approved for your vehicle by
Mercedes-Benz. These batteries provide
increased impact protection to prevent vehicle Battery (vehicle)
341Breakdown assistance Z

occupants from suffering acid burns should the
battery be damaged in the event of an accident.
In order for the battery to achieve the maximum possible service life, it must always be suffi-
ciently charged.
Like other batteries, the vehicle battery may
discharge over time if you do not use the vehicle. In this case, have the battery disconnected at a
qualified specialist workshop. However, you can also charge the battery with a charger recom-
mended by Mercedes-Benz. Contact a qualified
specialist workshop for further information.
Have the battery charge state checked more
frequently if you use the vehicle mainly for short trips or if you leave it standing idle for a lengthyperiod. Consult a qualified specialist workshop
if you wish to leave your vehicle parked for a long
period of time.
Remove the SmartKey if you park the vehicle
and do not require any electrical consumers.
The vehicle will then use very little energy, thus
conserving battery power.
If the power supply has been interrupted, e.g. if
you reconnect the battery, you will have to:
R set the clock (see the Digital Operator's Man-
ual)
On vehicles with a multimedia system and
navigation system, the clock is set automati-
cally.
R reset the function for automatically folding
the exterior mirrors in/out by folding the mir-
rors out once(Y page 111) 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 343).
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 343).
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 availability. Read the battery 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. 342
Battery (vehicle)Breakdown assistance

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.
Make sure that:
R The jumper cables are not damaged.
R Bare parts of the terminal clamp do not come into contact with other metal parts while the jumper
cables are connected to the battery.
R The jumper cables cannot come into contact with parts that can move when the engine is running,
such as the V-belt pulley or the fan.
X Secure the vehicle by applying the electric parking brake.
X Shift the transmission to position 005D.
X Make sure that the ignition is switched off. All indicator lamps in the instrument cluster must be
off. When using the SmartKey, turn the SmartKey to position 0092in the ignition lock and remove it
(Y page 140).
X Switch off all electrical consumers, e.g. rear window defroster, lighting, etc.
X Open the hood.
i Right-hand-drive vehicle:
the jump-starting connection points may be located on the other
side of the vehicle. 344
Jump-startingBreakdown assistance

Position number
0084identifies the charged battery of the other vehicle or an equivalent jump-starting
device.
X Slide cover 0043of positive terminal 0044in the direction of the arrow.
X Connect positive terminal 0044on your vehicle to positive terminal 0087of donor battery 0084using the
jumper cable, always begin with positive terminal 0044on your own vehicle first.
X Start the engine of the donor vehicle and run it at idling speed.
X Connect negative terminal 0085of donor battery 0084to ground point 0083of your vehicle using the
jumper cable, beginning with donor battery 0084first.
X Start the engine.
X Before disconnecting the jumper cables, let the engine run for several minutes.
X First, remove the jumper cables from ground point 0083and negative terminal 0085, then from pos-
itive terminal 0044and positive terminal 0087. Begin each time at the contacts on your own vehicle
first.
X Close cover 0043of positive terminal 0044after removing the jumper cables.
X Have the battery checked at a qualified specialist workshop.
Jump-starting is not considered to be a normal operating condition.
i Jumper cables and further information regarding jump-starting can be obtained at any qualified
specialist workshop. Jump-starting
345Breakdown assistance Z

X
Remove the SmartKey from the ignition lock.
Or, on vehicles with KEYLESS-GO start function
or KEYLESS‑GO:
X Open the driver's door.
The vehicle electronics are now in key posi-
tion 0092. This is the same as the SmartKey
having been removed.
The driver’s door can be closed again.
X Secure the vehicle against rolling away
(Y page 158).
All indicator lamps in the instrument cluster
must be off.
The fuses are located in various fuse boxes:
R Fuse box on the front-passenger side of the
dashboard
R Fuse box in the engine compartment on the
right-hand side of the vehicle, when viewed in
the direction of travel
R Fuse box under the rear bench seat Dashboard fuse box
! Do not use a pointed object such as a screw-
driver to open the cover in the dashboard. You
could damage the dashboard or the cover.
Mercedes-Benz recommends that you have this work performed at a qualified specialist work-
shop, e.g. at an authorized Mercedes-Benz Cen-
ter. X
Open the front-passenger door.
X To open: pull cover 0043outwards in the direc-
tion of the arrow and remove it.
X To close: clip in cover 0043on the front of the
dashboard.
X Fold cover 0043inwards 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 321).
X Use a dry cloth to remove any moisture from
the fuse box.
X To open: open clamps 0044.
X Fold up cover 0043in the direction of the arrow
and remove it.
X To close: check whether the seal is seated
correctly in cover 0043.
X Insert cover 0043at the side of the fuse box into
the retainers.
X Fold down cover 0043and close clamps 0044.
X Close the hood. Fuse box under the rear bench seat350
FusesBreakdown assistance

ponents may also be damaged. There is a risk
of an accident.
Rotate front and rear wheels only if the wheels
and tires are of the same dimensions.
! On vehicles equipped with a tire pressure
monitor, electronic components are located
in the wheel.
Tire-mounting tools should not be used near
the valve. This could damage the electronic
components.
Only have tires changed at a qualified spe-
cialist workshop.
Always observe the instructions and safety
notes in the "Mounting a wheel" section
(Y page 373).
The wear patterns on the front and rear tires
differ, depending on the operating conditions.
Rotate the wheels before a clear wear pattern
has formed on the tires. Front tires typically
wear more on the shoulders and the rear tires in
the center.
On vehicles that have the same size front and
rear wheels, you can rotate the wheels accord-
ing to the intervals in the tire manufacturer's
warranty book in your vehicle documents. If no
warranty book is available, the tires should be
rotated every 3,000 to 6,000 miles (5,000 to
10,000 km). Depending on tire wear, this may
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 359).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 335).
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
005D.
X Vehicles with the AIRMATIC package:
make sure that the normal vehicle level is
selected (Y page 187).
X Vehicles with the Off-Road Engineering
package:
make sure that the normal level is
selected (Y page 180).
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
0092. This means no SmartKey is in the ignition lock.
X Vehicles with KEYLESS-GO: remove the
Start/Stop button from the ignition lock
(Y page 140).
X If included in the vehicle equipment, remove
the tire-change tool kit from the vehicle.
X Safeguard the vehicle against rolling away.
i Apart from certain country-specific varia-
tions, vehicles are not equipped with a tire-
change tool kit. For more information on
which tools are required to perform a wheel
change on your vehicle, consult a qualified
specialist workshop. Changing a wheel
373Wheels and tires Z