2017 MERCEDES-BENZ GLS maintenance

G WARNING
Limbs could be crushed or trapped if the
engine is started unintentionally during ser-
vice or maintenance work. There is a risk of
injury.
Always secure the engine against uninten-
tional starting before carrying out mainte-
nance or repair work.
Make sure that the engine cannot be started via
your smartphone before carrying out mainte-
nance or repairs. You can prevent an engine
start via your smartphone, for example, if you: R
switch on the hazard warning lamps R
do not lock the doors R
open the hood
Pulling away
General notes
G WARNING
If the engine speed is above the idling speed
and you engage transmission position D or R ,
the vehicle could pull away suddenly. There is
a risk of an accident.
When engaging transmission position D or R ,
always firmly depress the brake pedal and do
not simultaneously accelerate.
Depress the accelerator carefully when pulling
away.
The vehicle locks centrally once you have pulled
away. The locking knobs in the doors drop down.
You can open the doors from the inside at any
time.
You can also deactivate the automatic locking
feature ( Y
page 239).
It is only possible to shift the transmission from
position P to the desired position if you depress
the brake pedal. Only then is the parking lock
released. If you do not depress the brake pedal,
the DIRECT SELECT lever can still be moved but
the parking lock remains engaged.
i Upshifts take place at higher engine speeds
after a cold start. This helps the catalytic con-
verter to reach its operating temperature
more quickly. Information on the automatic release of the
electric parking brake ( Y
page 161).
Pulling away with a trailer
To ensure that you do not roll backwards when
pulling away on an uphill slope, engage the elec-
tric parking brake. X
Press and hold handle C .
The electric parking brake continues to brake
and prevent the vehicle from rolling back-
wards.
The red I (USA only) or $ (Canada
only) indicator lamp in the instrument cluster
remains on. X
Depress the accelerator pedal. X
As soon as the vehicle/trailer combination is
held by the driving force of the engine, release
lever C .
the electric parking brake is released.
The red I (USA only) or $ (Canada
only) indicator lamp in the instrument cluster
goes out.
Hill start assist Hill start assist helps you when pulling away for-
wards or in reverse on an uphill gradient. It holds
the vehicle for a short time after you have
removed your foot from the brake pedal. This
gives you enough time to move your foot from
the brake pedal to the accelerator pedal and to
depress it before the vehicle begins to roll.
G WARNING
After a short time, hill start assist will no lon-
ger brake your vehicle and it could roll away.
There is a risk of an accident and injury.
Therefore, quickly move your foot from the
brake pedal to the accelerator pedal. Never Driving 141
Driving and parking Z

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 ‡(

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

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

Engine compartment
Hood
Important safety notes
G WARNING
If the hood is unlatched, it may open up when
the vehicle is in motion and block your view.
There is a risk of an accident.
Never unlatch the hood while driving. Before
every trip, ensure that the hood is locked.
G WARNING
When opening and closing the hood, it may
suddenly fall into the closed position. There is
a risk of injury to persons within range of
movement of the hood.
Open and close the hood only when no one is
within its range of movement.
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
The engine compartment contains moving
components. Certain components, such as
the radiator fan, may continue to run or start
again suddenly when the ignition is off. There
is a risk of injury.
If you need to do any work inside the engine
compartment: R
switch off the ignition R
never reach into the area where there is a
risk of danger from moving components,
such as the fan rotation area R
remove jewelry and watches R
keep items of clothing and hair, for exam-
ple, away from moving parts
G WARNING
The ignition system and the fuel injection sys-
tem work under high voltage. If you touch
components which are under voltage, you
could get an electric shock. There is a risk of
injury.
Never touch components of the ignition sys-
tem or fuel injection system when the ignition
is switched on.
Opening the hood
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
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.
! Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield wip-
ers or the hood.Engine compartment 319
Maintenance and care 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, for example with a winter front or
bug cover. The readings of the on-board-diag-
nostic system may otherwise be inaccurate.
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
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.
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.320
Engine compartment
Maintenance and care