2018 MERCEDES-BENZ GLS SUV check engine light

ProblemPossible causes/consequences andMSolutions
There is interference from a powerful source of radio waves.
XUnlock (Ypage 84) or lock (Ypage 84) the vehicle using the
mechanical key.
KEYLESS-GO is malfunctioning.
XLock/unlock the vehicle using the remote control function of the
SmartKey.
XHave the vehicle and SmartKey checked at a qualified specialist
workshop.
If the vehicle can also not be locked/unlocked using the remote con-
trol function:
XUnlock (Ypage 84) or lock (Ypage 84) the vehicle using the
mechanical key.
XHave the vehicle and SmartKey checked at a qualified specialist
workshop.
The engine cannot be
started using the Smart-
Key.The on-board voltage is too low.
XSwitch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work:
XCheck the starter battery and charge it if necessary (Ypage 346).
or
XJump-start the vehicle (Ypage 346).
or
XConsult a qualified specialist workshop.
The engine cannot be
started using the Start/
Stop button. The Smart-
Key is in the vehicle.The vehicle is locked.
XUnlock the vehicle and try to start the vehicle again.
The SmartKey battery is discharged or nearly discharged.
XCheck the SmartKey battery (Ypage 80) and replace it if necessary
(Ypage 80).
If this does not work:
XStart your vehicle with the SmartKey in the ignition lock.
There is interference from a powerful source of radio waves.
XStart your vehicle with the SmartKey in the ignition lock.
You have lost a Smart-
Key.XHave the SmartKey deactivated at a qualified specialist workshop.
XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
You have lost the
mechanical key.XReport the loss immediately to the vehicle insurers.
XIf necessary, have the locks changed as well.
82SmartKey
Opening and closing

Problems with the seat heating or seat ventilation
ProblemPossible causes/consequences andMSolutions
The seat heating or seat
ventilation has switched
off prematurely or can-
not be switched on.The on-board voltage is too low because too many electrical consum-
ers are switched on.
XSwitch off electrical consumers that you do not need, such as the
rear window defroster or interior lighting.
Once the battery is sufficiently charged, the seat heating or seat
ventilation will switch back on automatically.
Steering wheel
Important safety notes
GWARNING
You could lose control of your vehicle if you do the following while driving:
Radjust the driver's seat, head restraint,
steering wheel or mirrors
Rfasten the seat belt
There is a risk of an accident.
Adjust the driver's seat, head restraint, steer-
ing wheel and mirror and fasten your seat belt before starting the engine.
GWARNING
Children could injure themselves if they
adjust the steering wheel. There is a risk of
injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children unsupervised in the vehicle.
The electrically adjustable steering wheel can
still be adjusted when there is no SmartKey in
the ignition lock.
Adjusting the steering wheel man-
ually
GWARNING
If the steering wheel is unlocked while the
vehicle is in motion, it could change position
unexpectedly. This could cause you to lose
control of the vehicle. There is a risk of an
accident.
Before starting off, make sure the steering
wheel is locked. Never unlock the steering
wheel while the vehicle is in motion.
:Release lever
;Adjusts the steering wheel height
=Adjusts the steering wheel position (fore-
and-aft adjustment)
XPush release lever :down completely.
The steering column is unlocked.
XAdjust the steering wheel to the desired posi-
tion.
XPush release lever :up completely.
The steering column is locked.
XCheck if the steering column is locked. When
doing so, try to push the steering wheel up or down or try to move it in the fore-and-aft
direction.
108Steering wheel
Seats, steering wheel and mirrors

Replacing the rear window wiper blade
Removing a wiper blade
XRemove the SmartKey from the ignition lock.
XFold wiper arm:away from the rear window
until it engages.
XPosition wiper blade ;at a right angle to
wiper arm :.
XHold wiper arm :and press wiper blade ;
in the direction of the arrow until it releases.
XRemove wiper blade ;.
Installing a wiper blade
XPlace new wiper blade ;onto wiper arm :.
XHold wiper arm :and press wiper blade ;
in the opposite direction to the arrow until it
engages.
XMake sure that wiper blade ;is seated cor-
rectly.
XPosition wiper blade ;parallel to wiper
arm :.
XFold wiper arm :back onto the rear window.
Problems with the windshield wipers
ProblemPossible causes/consequences and MSolutions
The windshield wipers
are jammed.Leaves or snow, for example, may be obstructing the windshield wiper
movement. The wiper motor has been deactivated.
XFor safety reasons, you should remove the SmartKey from the igni-
tion lock.
or
XSwitch off the engine using the Start/Stop button and open the
driver's door.
XRemove the cause of the obstruction.
XSwitch the windshield wipers back on.
The windshield wipers
fail completely.The windshield wiper drive is malfunctioning.
XSelect another wiper speed on the combination switch.
XHave the windshield wipers checked at a qualified specialist work-
shop.
124Windshield wipers
Lights and windshield wipers

ignite if in contact with the exhaust system or
parts of the engine that heat up. There is a risk
of fire.
Carry out regular checks to make sure that
there are no flammable foreign materials in
the engine compartment or in the exhaust
system.
General notes
Vehicles with a gasoline engine:the catalytic
converter is preheated for up to 30 seconds
after a cold start. The sound of the engine may
change during this time.
Automatic transmission
XShift the transmission to position j
(Ypage 148).
The transmission position indicator on the
multifunction display shows j
(
Ypage 149).
iYou can start the engine in transmission
position jand i.
Starting procedure with the SmartKey
XTo start a diesel engine: turn the SmartKey
to position 2in the ignition lock
(
Ypage 140).
The % preglow indicator lamp in the instru-
ment cluster lights up.
XTurn the SmartKey to position 3in the igni-
tion lock (Ypage 140) and release it as soon
as the engine is running.
iVehicles with a diesel engine: you can
start the engine without preglow if the engine
is warm.
Using KEYLESS-GO to start the engine
The Start/Stop button can be used to start the
vehicle without inserting the SmartKey into the
ignition lock. The Start/Stop button must be
inserted in the ignition lock and the SmartKey
must be in the vehicle. This mode for starting the
engine operates independently of the ECO
start/stop automatic engine start function.
XDepress the brake pedal and keep it
depressed.
XPress the Start/Stop button once
(Ypage 140).
Vehicles with a gasoline engine: the engine
starts.
Vehicles with a diesel engine: preglow is
activated and the engine starts.
Starting procedure via smartphone
Observe the important safety notes on starting
the engine (Ypage 141).
You can also start your engine via your smart-
phone from outside the vehicle. In this case, the
previously selected climate control setting is
activated. In this way you can cool or heat the
interior of the vehicle before starting the jour-
ney.
Only start the engine via your smartphone if it is
safe to start and run the engine where your vehi-
cle is parked.
Observe the legal stipulations in the area where your vehicle is parked. Engine start via smart-
phone may be limited to certain countries or
regions.
You can execute a maximum of two consecutive
starting attempts via your smartphone. If you
insert the SmartKey into the ignition lock, you
can carry out two more starting attempts.
Once you have started the engine, you can
switch the engine off via your smartphone at any
time.
You can only start the engine via your smart-
phone if:
Rthe SmartKey is in the ignition lock
Rpark position jis selected
Rthe accelerator pedal is not depressed
Rthe anti-theft alarm system is not activated
Rthe panic alarm is not activated
Rthe hazard warning lamps are switched off
Rthe hood is closed
Rthe doors are closed and locked
Rthe windows and sliding sunroof are closed
Also make sure that:
Rthe fuel tank is sufficiently filled
Rthe starter battery is sufficiently charged
142Driving
Driving and parking

If indicator lamp;is off, the ECO start/stop
function has been deactivated manually or as
the result of a malfunction.
Problems with the engine
ProblemPossible causes/consequences and MSolutions
The engine does not
start. The starter motor
can be heard.RThere is a malfunction in the engine electronics.
RThere is a malfunction in the fuel supply.
Before attempting to start the engine again:
XTurn the SmartKey in the ignition lock back to position u.
or
XPress the Start/Stop button repeatedly until all indicator lamps in
the instrument cluster go out.
XTry to start the engine again (Ypage 141). Avoid excessively long
and frequent attempts to start the engine as these will drain the
battery.
If the engine does not start after several attempts:
XConsult a qualified specialist workshop.
The engine does not
start. You cannot hear
the starter motor.The on-board voltage is too low because the battery is too weak or
discharged.
XJump-start the vehicle (Ypage 346).
If the engine does not start despite attempts to jump-start it:
XConsult a qualified specialist workshop.
The starter motor was exposed to a thermal load that was too high.
XAllow the starter motor to cool down for approximately two minutes.
XTry to start the engine again.
If the engine still does not start:
XConsult a qualified specialist workshop.
Vehicles with a gasoline
engine:
The engine is not running
smoothly and is misfir-
ing.There is a malfunction in the engine electronics or in a mechanical
component of the engine management system.
XOnly depress the accelerator pedal slightly.
Otherwise, non-combusted fuel may get into the catalytic converter
and damage it.
XHave the cause rectified immediately at a qualified specialist work-
shop.
The coolant temperature
gage shows a value
above 248 ‡ (120 †).The coolant level is too low. The coolant is too hot and the engine is no
longer being cooled sufficiently.
XStop as soon as possible and allow the engine and the coolant to
cool down.
XCheck the coolant level (Ypage 328). Observe the warning notes
as you do so and add coolant if necessary.
146Driving
Driving and parking

Opening the fuel filler flap
:To open the fuel filler flap
;To insert the fuel filler cap
=Instruction label for fuel type to be refueled
?Tire pressure table
XSwitch off the engine.
XRemove the SmartKey from the ignition lock.
or, on vehicles with KEYLESS ‑GO:
XOpen the driver's door.
The vehicle electronics are now in key posi-
tion u. This is the same as the key having
been removed.
The driver’s door can be closed again.
XPress the fuel filler flap in the direction of
arrow :.
The fuel filler flap swings up.
XTurn the fuel filler cap counterclockwise and
remove it.
XInsert the fuel filler cap into the holder
bracket on the inside of filler flap ;.
XCompletely insert the filler neck of the fuel
pump nozzle into the tank, hook in place and
refuel.
XOnly fill the tank until the pump nozzle
switches off.
Do not add any more fuel after the pump stops
filling for the first time. Otherwise, fuel may leak
out.
Vehicles with a diesel engine: the filler neck is
designed for refueling at diesel filling pumps.
Closing the fuel filler flap
XReplace the cap on the filler neck and turn
clockwise until it engages audibly.
XClose the fuel filler flap.
Close the fuel filler flap before locking the vehi-
cle.
If you are driving with the fuel filler cap open, the
8 reserve fuel warning lamp flashes. A mes-
sage appears in the multifunction display
(
Ypage 263).
In addition, the ;Check Engine warning
lamp may light up (
Ypage 288).
Refueling157
Driving and parking
Z

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
GWARNING
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.
RBrake occasionally to remove any possible
salt residue. Make sure that you do not
endanger other road users when doing so.
RCarefully depress the brake pedal and the
beginning and end of a journey.
RMaintain a greater distance to the vehicle
ahead.
Servicing the brakes
!The brake fluid level may be too low, if:
Rif the red brake warning lamp lights up in
the instrument cluster and
Ryou 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 0or 1or Start/Stop
button in position 0or 1) when the electric
Driving tips167
Driving and parking
Z

Familiarize yourself with the characteristics of
your vehicle and the gear shift operation before
driving through difficult terrain.
The following driving systems are specially
adapted to off-road driving:
RtheOff-road drive program (vehicles without
Off-Road Engineering package)
(
Ypage 219)
ROff-road andOff-road Plus drive programs
(vehicles with Off-Road Engineering package)
(
Ypage 220)
RLOW RANGE off-road gear (vehicles with the
Off-Road Engineering package)
(
Ypage 221)
RDifferential lock (vehicles with the Off-Road
Engineering package) (Ypage 221)
ROff-road ABS (Ypage 67)
ROff-road 4ETS (Ypage 70)
ROff-road ESP®(Ypage 71)
RAIRMATIC package (vehicle level)
(Ypage 188)
RDSR (Downhill Speed Regulation)
(Ypage 218)
Observe the following notes:
RStop the vehicle before starting to drive along
an off-road route. If necessary, select the off- road program (
Ypage 220) or shift to the
LOW RANGE off-road gear (Ypage 221).
RSelect a vehicle level that is suitable for the
terrain. To avoid damaging the vehicle, make
sure there is always sufficient ground clear-
ance.
RCheck that items of cargo and loads are
stowed safely and are well secured
(
Ypage 305).
RAlways keep the engine running and in gear
when driving on a downhill gradient. Activate
DSR (
Ypage 218).
RAlways keep the engine running and in gear
when driving down an incline.
RAdapt your speed to the terrain. The rougher,
steeper or more ruts on the terrain, the slower
your speed should be.
RDo not jump with the vehicle as this will inter- rupt the vehicle's propulsion.
RDrive with extreme care on unfamiliar off-road
routes where visibility is poor. For safety rea-
sons, get out of the vehicle first and survey
the off-road route.
RLook out for obstacles, such as rocks, holes,
tree stumps and furrows.
RTake care when turning on an uphill or down-hill slope or when driving across a slope. The
vehicle could otherwise tip over.
RAlways keep the doors, the tailgate, the side
windows and the sliding sunroof closed whilethe vehicle is in motion.
RDo not shift the automatic transmission to
position i.
RObserve the notes on off-road fording
(Ypage 169).
iInformation about retrofitting special all-ter-
rain tires is available from any qualified spe-
cialist workshop.
iDo not use the HOLD function when driving
off-road, on steep uphill or downhill gradients
or on slippery or loose surfaces. The HOLD
function cannot hold the vehicle on such sur-
faces.
Checklist before driving off-road
!If the engine oil warning lamp lights up while
the vehicle is in motion, stop the vehicle in a
safe place as soon as possible. Check the
engine oil level. The engine oil warning lamp
warning must not be ignored. Continuing the
journey while the symbol is displayed could
lead to engine damage.
XEngine oil level: check the engine oil level
and add oil if necessary.
When driving on steep gradients, the engine
oil level must be sufficiently high to ensure a
correct oil supply in the vehicle.
XDEF tank (BlueTEC vehicles): check the
level and add if necessary (Ypage 158).
XTire-changing tool kit: check that the jack is
working and make sure you have the lug
wrench, a robust tow cable and a folding
spade in the vehicle.
XWheels and tires: check the tread depth and
pressure of the tires.
XCheck for damage and remove any foreign
objects, e.g. small stones, from the wheels/
tires.
XReplace any missing valve caps.
XReplace dented or damaged wheels.
XRims: dented or bent rims can result in a loss
of tire pressure and damage the tire bead.
Driving tips171
Driving and parking
Z