engine MERCEDES-BENZ GLS 2017 Repair Manual

Problems with the transmission Problem
Possible causes/consequences and P Solutions
The transmission has
problems shifting gear. The transmission is losing oil. X
Have the transmission checked at a qualified specialist workshop
immediately.
7G-TRONIC:
The acceleration ability
is deteriorating.
The transmission no lon-
ger changes gear. The transmission is in emergency mode.
It is only possible to shift into second gear and reverse gear.X
Stop the vehicle. X
Shift the transmission to position P .X
Switch off the engine. X
Wait at least ten seconds before restarting the engine. X
Shift the transmission to position D or R .
If D is selected, the transmission shifts into second gear; if R is
selected, the transmission shifts into reverse gear. X
Have the transmission checked at a qualified specialist workshop
immediately.
9G-TRONIC:
The acceleration ability
is deteriorating.
The transmission no lon-
ger changes gear. The transmission is in emergency mode.
It is only partly possible to engage the gears or the transmission is in
position N . X
Stop the vehicle. X
Shift the transmission to position P .X
Switch off the engine. X
Wait at least ten seconds before restarting the engine. X
Shift the transmission to position D or R .X
Have the transmission checked at a qualified specialist workshop
immediately.
Transfer case This section is only valid for vehicles with 4-
wheel drive (4MATIC). Power is always trans-
mitted to both axles.
! Performance tests may only be carried out
on a 2-axle dynamometer. The brake system
or transfer case could otherwise be damaged.
Contact a qualified specialist workshop for a
performance test.
! Because ESP ®
is an automatic system, the
engine and ignition must be switched off
(SmartKey in position 0 or 1 or Start/Stop
button in position 0 or 1 ) when the electric
parking brake is being tested on a brake dyna-
mometer (maximum 10 seconds).
Braking triggered automatically by ESP ®
may
seriously damage the brake system. ! Vehicles with 4MATIC must not be towed
with either the front or the rear axle raised, as
doing so will damage the transmission.
Refueling
Important safety notes
G WARNING
Fuel is highly flammable. If you handle fuel
incorrectly, there is a risk of fire and explo-
sion.
You must avoid fire, open flames, creating
sparks and smoking. Switch off the engine
and, if applicable, the auxiliary heating before
refueling. Refueling 153
Driving and parking Z

G WARNING
Fuel is poisonous and hazardous to health.
There is a risk of injury.
You must make sure that fuel does not come
into contact with your skin, eyes or clothing
and that it is not swallowed. Do not inhale fuel
vapors. Keep fuel away from children.
If you or others come into contact with fuel,
observe the following: R
Wash away fuel from skin immediately
using soap and water. R
If fuel comes into contact with your eyes,
immediately rinse them thoroughly with
clean water. Seek medical assistance with-
out delay. R
If fuel is swallowed, seek medical assis-
tance without delay. Do not induce vomit-
ing. R
Immediately change out of clothing which
has come into contact with fuel.
G WARNING
Electrostatic buildup can create sparks and
ignite fuel vapors. There is a risk of fire and
explosion.
Always touch the vehicle body before opening
the fuel filler flap or touching the fuel pump
nozzle. Any existing electrostatic buildup is
thereby discharged.
G WARNING
Vehicles with a diesel engine:
If you mix diesel fuel with gasoline, the flash
point is lower than that of pure diesel fuel.
When the engine is running, exhaust system
components could overheat without being
noticed. There is a risk of fire.
Never refuel with gasoline. Never mix gasoline
with diesel fuel.
! Do not use gasoline to refuel vehicles with a
diesel engine. Do not switch on the ignition if
you accidentally refuel with the wrong fuel.
Otherwise, the fuel will enter the fuel system.
Even small amounts of the wrong fuel could
result in damage to the fuel system and the engine. The repair costs are high. Notify a
qualified specialist workshop and have the
fuel tank and fuel lines drained completely.
! Do not use diesel to refuel vehicles with a
gasoline engine. Do not switch on the ignition
if you accidentally refuel with the wrong fuel.
Otherwise, the fuel will enter the fuel system.
Even small amounts of the wrong fuel could
result in damage to the fuel system and the
engine. Notify a qualified specialist workshop
and have the fuel tank and fuel lines drained
completely.
! Overfilling the fuel tank could damage the
fuel system.
! Take care not to spill any fuel on painted
surfaces. You could otherwise damage the
paintwork.
! Use a filter when adding fuel from a fuel can.
The fuel lines and/or the fuel injection system
could otherwise be blocked by particles from
the fuel can.
Do not get into the vehicle again during the refu-
eling process. Otherwise, electrostatic charge
could build up again.
If you overfill the fuel tank, fuel could spray out
when the fuel pump nozzle is removed.
For further information on fuel and fuel quality
( Y
page 379).
Refueling
General information Pay attention to the important safety notes
( Y
page 153).
The fuel filler flap is unlocked or locked auto-
matically when you unlock or lock the vehicle
with the SmartKey or using KEYLESS-GO.
The position of the fuel filler cap is displayed

Problems with fuel and the fuel tank Problem
Possible causes/consequences and P Solutions
Fuel is leaking from the
vehicle.
G WARNING
The fuel line or the fuel tank is faulty.
Risk of explosion or fire. X
Apply the electric parking brake. X
Switch off the engine. X
Remove the SmartKey from the ignition lock.
or, on vehicles with KEYLESS ‑ GO:X
Open the driver's door.
The on-board electronics now have status 0 . This is the same as the
SmartKey having been removed. X
Do not restart the engine under any circumstances. X
Consult a qualified specialist workshop.
The engine does not
start. The fuel tank of a vehicle with a diesel engine has been run completely
dry. X
Refuel the vehicle with at least 5.3 US qt (5 liters) of diesel. X
Turn the ignition on for approximately ten seconds ( Y
page 138).X
Start the engine continuously for up to ten seconds until it runs
smoothly.
If the engine does not start: X
Turn the ignition on again for approximately ten seconds
( Y
page 138). X
Start the engine again continuously for up to ten seconds until it
runs smoothly.
If the engine does not start after three attempts: X
Consult a qualified specialist workshop.
The fuel filler flap cannot
be opened. The fuel filler flap is not unlocked. X
Unlock the vehicle ( Y
page 74).
The SmartKey battery is discharged or nearly discharged. X
Unlock the vehicle using the mechanical key ( Y
page 76).
The fuel filler flap is unlocked, but the opening mechanism is jammed. X
Consult a qualified specialist workshop.
DEF (BlueTEC vehicles only)
General notes
To function properly, BlueTEC exhaust gas after-
treatment must be operated with the reducing
agent DEF. Adding DEF is one of the tasks per-
formed during maintenance. Under normal operating conditions, a tank of DEF lasts until
the next service due date.
When the supply of DEF is almost used up, the
Check Additive See Operator's Manual
message is shown in the multifunction display.
If you drive the vehicle faster than 10 mph
(16 km/h), the Check Additive See Opera‐156
Refueling
Driving and parking

tor's Manual message goes out after approx-
imately one minute.
When the DEF supply drops to a minimum, the
Remaining Starts: 16 message is shown in
the multifunction display.
If the Remaining Starts: 16 message
appears in the multifunction display, you can
start the engine another 16 times. If DEF is not
refilled, you will subsequently be unable to
start the engine .X
Add at least 1 gal (3.8 l) of DEF.X
Switch on the ignition for at least 60 seconds. X
Start the engine.
i Have the DEF tank refilled at a qualified spe-
cialist workshop.
Use the special DEF refill bottle when adding
DEF between maintenance intervals. You can
obtain further information from an authorized
Mercedes-Benz Center or, if necessary, contact
Roadside Assistance ( Y
page 27).
If the outside temperature is below 12 ‡(

overfilling. DEF may leak if overfilled. Mercedes-
Benz offers a special disposable hose with over-
fill protection. You can obtain this from any
authorized Mercedes-Benz Center. DEF is avail-
able in a variety of containers and receptacles.
Only use the disposable hose with the
Mercedes-Benz DEF refill canisters.
DEF refill bottle
! Only screw on the DEF refill bottle hand-
tight. Otherwise, the thread of the DEF refill
bottle could be damaged and DEF could leak
out.
X
Unscrew the protective cap from DEF refill
bottle C .X
Place DEF refill bottle C on the filler neck as
shown and screw it on clockwise until hand-
tight. X
Press DEF refill bottle C towards the filler
neck.
The DEF tank is filled. This may take up to one
minute.
i When DEF refill bottle C is no longer
pressed, filling stops and the bottle may be
taken off again after being only partially emp-
tied. X
Release DEF refill bottle C .X
Turn DEF refill bottle C counter-clockwise
and remove it. X
Screw the protective cap onto DEF refill bot-
tle C again.
DEF refill canisters are available at many gas
stations or at a qualified specialist workshop.
Refill bottles without a threaded cap do not pro-
vide overfill protection. DEF may leak if overfil-
led. Mercedes Benz offers special refill bottles
with a threaded seal. These are available at any
authorized Mercedes-Benz Center. Parking
Important safety notes
G WARNING
Flammable material such as leaves, grass or
twigs may ignite if they come into contact with
hot parts of the exhaust system or exhaust
gas flow. There is a risk of fire.
Park the vehicle so that no flammable mate-
rials come into contact with parts of the vehi-
cle which are hot. Take particular care not to
park on dry grassland or harvested grain
fields.
G WARNING
If you leave children unsupervised in the vehi-
cle, they could set it in motion by, for example: R
release the parking brake. R
shift the automatic transmission out of the
parking position P . R
start the engine.
In addition, they may operate vehicle equip-
ment and become trapped. There is a risk of
an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children unsupervised in the vehicle.
! Always secure the vehicle correctly against
rolling away. Otherwise, the vehicle or its driv-
etrain could be damaged.
To ensure that the vehicle is secured against
rolling away unintentionally: R
the electric parking brake must be applied. R
the transmission must be in position P and the
SmartKey must be removed from the ignition
lock. R
the front wheels must be turned towards the
curb on steep uphill or downhill gradients. R
the empty vehicle must be secured at the
front axle with a wheel chock or similar, for
example, on uphill or downhill gradients. R
a laden vehicle must also be secured at the
rear axle with a wheel chock or similar, for
example, on uphill or downhill gradients. Parking 159
Driving and parking Z

Switching off the engine
G WARNING
The automatic transmission switches to neu-
tral position N when you switch off the engine.
The vehicle may roll away. There is a risk of an
accident.
After switching off the engine, always switch
to parking position P . Prevent the parked vehi-
cle from rolling away by applying the parking
brake. X
Apply the electric parking brake. X
Shift the transmission to position P .X
With the SmartKey: turn the SmartKey to
position 0 in the ignition lock and remove it.
The immobilizer is activated. X
With KEYLESS-GO:
Press the Start/Stop button ( Y
page 138)
The engine stops and all the indicator lamps in
the instrument cluster go out.
If you switch the engine off with the transmis-
sion in position R or D , the automatic transmis-
sion shifts to N automatically.
If you then open the driver's or front-passenger
door, the automatic transmission shifts to P
automatically.
If you want the automatic transmission to
remain in neutral N , e.g. when having the vehicle
cleaned in an automatic car wash with a towing
system: X
Vehicles with a SmartKey: switch on the
ignition. X
Vehicles with KEYLESS-GO: remove the
Start/Stop button from the ignition lock. X
Insert the SmartKey into the ignition lock. X
Switch on the ignition. X
All vehicles: depress the brake pedal and
keep it depressed. X
Shift to neutral N .X
Release the brake pedal. X
Release the electric parking brake. X
Switch off the ignition and leave the SmartKey
in the ignition lock.
i The engine can be switched off in an emer-
gency while the vehicle is in motion by press-
ing and holding the Start/Stop button for
three seconds. Electric parking brake
General notes
G WARNING
If you leave children unsupervised in the vehi-
cle, they could set it in motion by, for example: R
release the parking brake. R
shift the automatic transmission out of the
parking position P .R
start the engine.
In addition, they may operate vehicle equip-
ment and become trapped. There is a risk of
an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children unsupervised in the vehicle.
The function of the electric parking brake is
dependent on the on-board voltage. If the on-
board voltage is low or there is a malfunction in
the system, it may not be possible to apply the
released parking brake. X
If this is the case, only park the vehicle on
level ground and secure it to prevent it rolling
away. X
Shift the automatic transmission to position
P .
It may not be possible to release an applied
parking brake if the on-board voltage is low or
there is a malfunction in the system. Contact a
qualified specialist workshop.
i The electric parking brake performs a func-
tion test at regular intervals while the engine
is switched off. The sounds that can be heard
while this is occurring are normal.160
Parking
Driving and parking

Emergency braking
The vehicle can also be braked during an emer-
gency by using the electric parking brake. X
While driving, push handle C of the electric
parking brake.
The vehicle is braked for as long as the handle
of the electric parking brake is pressed. The
longer the electric parking brake handle is
depressed, the greater the braking force.
During braking: R
a warning tone sounds R
the Release Park. Brake message appearsR
the red I (USA only) or $ (Canada
only) indicator lamp in the instrument cluster
flashes
When the vehicle has been braked to a stand-
still, the electric parking brake is engaged.
Parking the vehicle for a long period If you leave the vehicle parked for longer than
four weeks, the battery may be damaged by
exhaustive discharging.
If you leave the vehicle parked for longer than six
weeks, the vehicle may suffer damage as a
result of lack of use. X
Visit a qualified specialist workshop and seek
advice.
i You can obtain information about trickle
chargers from a qualified specialist work-
shop. Driving tips
General notes
Important safety notes
G WARNING
If you switch off the ignition while driving,
safety-relevant functions are only available
with limitations, or not at all. This could affect,
for example, the power steering and the brake
boosting effect. You will require considerably
more effort to steer and brake. There is a risk
of an accident.
Do not switch off the ignition while driving.
G WARNING
If you operate mobile communication equip-
ment while driving, you will be distracted from
traffic conditions. You could also lose control
of the vehicle. There is a risk of an accident.
Only operate this equipment when the vehicle
is stationary.
Observe the legal requirements for the country
in which you are driving. Some jurisdictions pro-
hibit the driver from using a mobile phone while
driving a vehicle.
If you make a call while driving, always use
hands-free mode. Only operate the telephone
when the traffic situation permits. If you are
unsure, pull over to a safe location and stop
before operating the telephone.
Bear in mind that at a speed of only 30 mph
(approximately 50 km/h), the vehicle covers a
distance of 44 ft (approximately 14 m) per sec-
ond.
Drive sensibly – save fuel Observe the following tips to save fuel: X
The tires should always be inflated to the rec-
ommended tire pressure. X
Remove unnecessary loads. X
Remove roof carriers when they are not nee-
ded. X
Warm up the engine at low engine speeds. X
Avoid frequent acceleration or braking. X
Have all maintenance work carried out as
indicated by the service intervals in the Main-162
Driving tips
Driving and parking

tenance Booklet or by the service interval dis-
play.
Fuel consumption also increases when driving in
cold weather, in stop-start traffic and in hilly ter-
rain.
Drinking and driving
G WARNING
Drinking and driving and/or taking drugs and
driving are very dangerous combinations.
Even a small amount of alcohol or drugs can
affect your reflexes, perceptions and judg-
ment.
The possibility of a serious or even fatal acci-
dent is greatly increased when you drink or
take drugs and drive.
Do not drink or take drugs and drive or allow
anyone to drive who has been drinking or tak-
ing drugs.
Emission control
G WARNING
Combustion engines emit poisonous exhaust
gases such as carbon monoxide. Inhaling
these exhaust gases leads to poisoning. There
is a risk of fatal injury. Therefore never leave
the engine running in enclosed spaces with-
out sufficient ventilation.
Certain engine systems are designed to keep
the level of poisonous components in exhaust
fumes within legal limits.
These systems only work at peak efficiency if
they are serviced exactly in accordance with the
manufacturer's specifications. Always have
work on the engine carried out at a qualified
specialist workshop. Mercedes-Benz recom-
mends that you use an authorized Mercedes-
Benz Center for this purpose. In particular, work
relevant to safety or on safety-related systems
must be carried out at a qualified specialist
workshop.
The engine settings must not be changed under
any circumstances. Furthermore, all specific
service work must be carried out at regular
intervals and in accordance with the Mercedes-
Benz service requirements. Details can be found
in the Maintenance Booklet. ECO display The ECO display shows you how economical
your driving style is. The ECO display assists you
in achieving the most economical driving style
for the selected settings and prevailing condi-
tions. Your driving style can significantly influ-
ence the vehicle's consumption.
C
Acceleration D
Coasting

This helps you to avoid overheating the
brakes and wearing them out excessively.
When you take advantage of engine braking, a
drive wheel may not turn for some time, e.g.
on a slippery road surface. This could cause
damage to the drive train. This type of damage
is not covered by the Mercedes-Benz war-
ranty.
Do not depress the brake pedal continuously
while the vehicle is in motion, e.g. causing the
brakes to rub by constantly applying light pres-
sure to the pedal. This results in excessive and
premature wear to the brake pads.
Use the left-hand steering wheel paddle shifter
to shift into a lower gear in good time on long
and steep downhill gradients. This is especially
important if the vehicle is laden.
This also applies if you have activated cruise
control, the speed limiter or Distance Pilot
DISTRONIC.
This will use the braking effect of the engine, so
that less braking will be required to maintain the
speed. This relieves the load on the brake sys-
tem and prevents the brakes from overheating
and wearing too quickly.
Heavy and light loads
G WARNING
If you rest your foot on the brake pedal while
driving, the braking system can overheat. This
increases the stopping distance and can even
cause the braking system to fail. There is a
risk of an accident.
Never use the brake pedal as a footrest. Never
depress the brake pedal and the accelerator
pedal at the same time.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
If the brakes have been subjected to a heavy
load, do not stop the vehicle immediately. Drive
on for a short while. This allows the airflow to
cool the brakes more quickly.
Wet roads
If you have driven for a long time in heavy rain
without braking, there may be a delayed reac-
tion from the brakes when braking for the first time. This may also occur after the vehicle has
been washed or driven through deep water.
You then have to depress the brake pedal more
firmly. Maintain a greater distance from the
vehicle in front.
After driving on a wet road or having the vehicle
washed, brake firmly while paying attention to
the traffic conditions. This will warm up the
brake discs, thereby drying them more quickly
and protecting them against corrosion.
Limited braking performance on salt-
treated roads If you drive on salted roads, a layer of salt resi-
due may form on the brake discs and brake
pads. This can result in a significantly longer
braking distance. R
Brake occasionally to remove any possible
salt residue. Make sure that you do not
endanger other road users when doing so. R
Carefully depress the brake pedal and the
beginning and end of a journey. R
Maintain a greater distance to the vehicle
ahead.
Servicing the brakes
! The brake fluid level may be too low, if: R
if the red brake warning lamp lights up in
the instrument cluster and R
you hear a warning tone while the engine is
running
Observe additional warning messages in the
multifunction display.
The brake fluid level may be too low due to
brake pad wear or leaking brake lines.
Have the brake system checked immediately.
Consult a qualified specialist workshop to
arrange this.
! A function or performance test should only
be carried out on a 2-axle dynamometer. If
you wish to operate the vehicle on such a
dynamometer, please consult a qualified spe-
cialist workshop in advance. You could oth-
erwise damage the drive train or the brake
system.
! Because ESP ®
is an automatic system, the
engine and ignition must be switched off
(SmartKey in position 0 or 1 or Start/Stop
button in position 0 or 1 ) when the electricDriving tips 165
Driving and parking Z

parking brake is being tested on a brake dyna-
mometer (maximum 10 seconds).
Braking triggered automatically by ESP ®
may
seriously damage the brake system.
All checks and maintenance work on the brake
system must be carried out at a qualified spe-
cialist workshop.
Have brake pads installed and brake fluid
replaced at a qualified specialist workshop.
If the brake system has only been subject to
moderate loads, you should test the functional-
ity of your brakes at regular intervals. To do so,
depress the brake pedal firmly when driving at a
high speed. This improves the grip of the brake
pads.
You can find a description of Brake Assist (BAS)
on ( Y
page 64) or of BAS PLUS on ( Y
page 69).
Mercedes-Benz recommends that you only have
brake pads/linings installed on your vehicle
which have been approved for Mercedes-Benz
vehicles or which correspond to an equivalent
quality standard. Brake pads/linings which have
not been approved for Mercedes-Benz vehicles
or which are not of an equivalent quality could
affect your vehicle's operating safety.
Mercedes-Benz recommends that you only use
brake fluid that has been specially approved for
your vehicle by Mercedes-Benz, or which corre-
sponds to an equivalent quality standard. Brake
fluid which has not been approved for
Mercedes-Benz vehicles or which is not of an
equivalent quality could affect your vehicle's
operating safety.
High-performance brake system
(Mercedes-AMG vehicles) The high-performance brake system is designed
for heavy loads. This may lead to noise when
braking. This will depend on: R
Speed R
Braking force R
Environmental conditions, such as tempera-
ture and humidity
The wear of individual components of the brake
system, such as the brake pads/linings or brake
discs, depends on the individual driving style
and operating conditions.
For this reason, it is impossible to state a mile-
age that will be valid under all circumstances. An
aggressive driving style will lead to high wear. You can obtain further information about this
from your authorized Mercedes-Benz Center.
New and replaced brake pads and discs only
reach their optimum braking effect after several
hundred kilometers of driving. Compensate for
this by applying greater force to the brake pedal.
Keep this in mind, and adapt your driving and
braking accordingly during this break-in period.
Excessive heavy braking results in correspond-
ingly high brake wear. Observe the & brake
wear warning lamp in the instrument cluster and
note any brake status messages in the multi-
function display. Especially for high perform-
ance driving, it is important to maintain and have
the brake system checked regularly.
Driving on wet roads
Hydroplaning If water has accumulated to a certain depth on
the road surface, there is a danger of hydro-
planing occurring, even if: R
you drive at low speeds. R
the tires have adequate tread depth.
For this reason, in the event of heavy rain or in
conditions in which hydroplaning may occur,
you must drive in the following manner: R
lower your speed. R
avoid ruts. R
avoid sudden steering movements. R
brake carefully.
Driving on flooded roads
! Do not drive through flooded areas. Check
the depth of any water before driving through
it. Drive slowly through standing water. Oth-
erwise, water may enter the vehicle interior or
the engine compartment. This can damage
the electronic components in the engine or
the automatic transmission. Water can also
be drawn in by the engine's air suction nozzles
and this can cause engine damage.
i Vehicles with the AIRMATIC package:
select the raised vehicle level before driving
through a body of water.166
Driving tips
Driving and parking