check engine MERCEDES-BENZ GLS SUV 2016 Service Manual

Problem
Possible causes/consequences and
M
MSolutions Unlocking using the
button in the driver's
door:
The ball coupling does
not swivel, even though:
R the vehicle is station-
ary
R no trailer cable is con-
nected The on-board voltage is too low.
X Engage park position P.
X Switch on the power supply.
or X Start the engine.
If the ball coupling still does not unlock: X Consult a qualified specialist workshop. The ball coupling does
not swivel. The indicator
lamp in the button is
flashing permanently.
The
Check trailer Check trailer
hitch lock
hitch lock message
appears in the multifunc- tion display. There is a malfunction in the release electronics.
X When the ball coupling is retracted: pull and hold the button in
the tailgate until the ball coupling engages into a securely engaged
and locked in a vertical position and then engages again under the
bumper.
X When the ball coupling is extended: pull and hold the button in
the tailgate until the ball coupling engages underneath the bumper.
If the ball coupling still does not unlock:
X Consult a qualified specialist workshop. 240
Towing a trailerDriving and parking

Important safety notes
G
WARNING
Operating the integrated information systems and communications equipment in the vehicle
while driving will distract you from traffic con-
ditions. You could then lose control of the
vehicle. There is a risk of an accident.
Only operate these devices if road traffic con-
ditions permit. If you are unsure about the
surrounding conditions, pull over to a safe
location and make entries only while the vehi-
cle is stationary.
You must observe the legal requirements for the country in which you are currently driving whenoperating the on-board computer. G
WARNING
If the instrument cluster has failed or mal-
functioned, you may not recognise function
restrictions relevant to safety. The operating
safety of your vehicle may be impaired. There is a risk of an accident.
Drive on carefully. Have the vehicle checked
at a qualified specialist workshop immedi-
ately.
If the operating safety of your vehicle is
impaired, park the vehicle safely as soon as pos-
sible. Contact a qualified specialist workshop.
The on-board computer shows only messages or warnings from certain systems on the multi-
function display. You should therefore make
sure your vehicle is operating safely at all times.
For an overview, see the instrument cluster illus-
tration (Y page 35). Displays and operation
Instrument cluster lighting
The lighting in the instrument cluster, in the dis-
plays and the controls in the vehicle interior can be adjusted using the brightness control knob.
The brightness control knob is located on the
bottom left of the instrument cluster
(Y page 35). X
Turn the brightness control knob clockwise or
anti-clockwise.
If you turn the light switch to Ã,Tor
L, the brightness is dependent upon the
brightness of the ambient light.
i The light sensor in the instrument cluster
automatically controls the brightness of the
multifunction display.
In daylight, the displays in the instrument
cluster are not illuminated. Speedometer with segments
The segments in the speedometer indicate
which speed range is available.
R Cruise control activated (Y page 180):
The segments light up from the stored speed to the maximum speed.
R Variable speed limiter is activated
(Y page 182):
The segments light up from the start of the
scale to the selected speed limitation.
R Distance Pilot DISTRONIC is activated
(Y page 184):
One or two segments in the stored speed
range light up.
R Distance Pilot DISTRONIC detects a vehicle in
front moving more slowly than the stored
speed:
The segments between the speed of the vehi- cle in front and the stored speed light up. Rev counter
! Do not drive in the overrevving range. Doing
so will damage the engine.
The red band in the rev counter indicates the
engine's overrevving range.
The fuel supply is interrupted to protect the
engine when the red band is reached. Outside temperature display
You should pay special attention to road condi-
tions when temperatures are around freezing
point. Displays and operation
241On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions The yellow
!warning lamp lights up. If you manually apply or
release the electric parking brake, the red !indicator lamp
flashes.
The electric parking brake is malfunctioning. The electric parking
brake cannot be applied manually.
X Shift the transmission to position P.
X Consult a qualified specialist workshop. !
Parking brake inop‐ Parking brake inop‐
erative erative The yellow
!warning lamp lights up. The red !indicator lamp
flashes for about ten seconds after the electric parking brake has been applied or released. It then goes out or remains lit.
The electric parking brake is malfunctioning, e.g. because of over-
voltage or undervoltage.
X Rectify the cause of the overvoltage or undervoltage, e.g. by charg-
ing the battery or restarting the engine.
X Apply or release the electric parking brake.
If the electric parking brake still cannot be applied or released: X Turn the ignition off and then back on.
X Apply or release the electric parking brake.
If the electric parking brake still cannot be released:
X Consult a qualified specialist workshop.
If the electric parking brake still cannot be applied:
X Consult a qualified specialist workshop. The yellow
!warning lamp lights up and the red !indicator
lamp flashes.
The electric parking brake cannot be applied manually.
X Shift the transmission to position P.
X Consult a qualified specialist workshop. J
Check brake fluid Check brake fluid
level level There is insufficient brake fluid in the brake fluid reservoir. In addition,
the J warning lamp in the instrument cluster lights up and a warn-
ing tone sounds.
G WARNING
Braking efficiency may be impaired.
There is a risk of an accident.
X Stop the vehicle immediately, paying attention to road and traffic
conditions. Do not continue driving.
X Secure the vehicle against rolling away (Y page 168).
X Consult a qualified specialist workshop.
X Do not top up the brake fluid. This does not correct the fault. #
Check Check
brake
brakepad
padwear
wear The brake pads/linings have reached their wear limit.
X Consult a qualified specialist workshop. Display
messages
263On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions b
Switch on headlamps Switch on headlamps You are driving without dipped-beam headlamps.
X
Turn the light switch to the Lorà position. Adaptive Highbeam Adaptive Highbeam
Assist Plus cur‐ Assist Plus cur‐
rently unavailable rently unavailable
See Owner's Manual See Owner's Manual Adaptive Highbeam Assist Plus is deactivated and temporarily inop-
erative.
Possible causes:
R The windscreen is dirty in the camera's field of vision.
R Visibility is impaired due to heavy rain, snow or fog.
X Clean the windscreen.
If the system detects that the camera is fully operational again, the Adaptive Highbeam Assist Plus available again Adaptive Highbeam Assist Plus available again message is
displayed.
Adaptive Highbeam Assist Plus is operational again. Adaptive Highbeam Adaptive Highbeam
Assist Plus inoper‐ Assist Plus inoper‐
ative ative Adaptive Highbeam Assist Plus is faulty.
X Consult a qualified specialist workshop. Engine
Display messages
Possible causes/consequences and
M
MSolutions +
Top up coolant See Top up coolant See
Owner's Manual Owner's Manual The coolant level is too low.
! Avoid making long journeys with too little coolant in the engine
cooling system. The engine will otherwise be damaged.
X Top up the coolant, observing the warning notes before doing so
(Y page 335).
If you have to top up the coolant frequently: X Contact a qualified specialist workshop and have the engine cooling
system checked. ? The fan motor is faulty.
X If the coolant temperature is below 120 †, continue driving to the
nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in moun-
tainous terrain and stop-start traffic. Display
messages
271On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions #
Stop vehicle See Stop vehicle See
Owner's Manual Owner's Manual The battery is no longer being charged and the battery charge level is
too low.
A warning tone also sounds.
X Stop the vehicle immediately, paying attention to road and traffic
conditions, and switch off the engine.
X Safeguard the vehicle against rolling away (Y page 168).
X Observe the instructions in the #See SeeOwner's
Owner's Manual
Manualdisplay
message.
X Consult a qualified specialist workshop. 4
Check Check
eng.
eng.oil
oillev.
lev.
when
when next
nextrefuelling
refuelling The engine oil level has dropped to the minimum level.
A warning tone also sounds.
! Avoid long journeys when there is too little coolant in the cooling
system. Otherwise the engine will be damaged.
X Check the oil level when next refuelling, at the latest (Y page 334).
X If necessary, top up the engine oil (Y page 334).
If you have to top up the engine oil frequently:
X Contact a qualified specialist workshop and have the engine
checked.
Information on approved engine oils can be obtained from any quali-
fied specialist workshop or on the Internet at http://bevo.mercedes-
benz.co m. 4
Add 1 litre engine Add 1 litre engine
oil when next refu‐ oil when next refu‐
elling elling Mercedes-AMG vehicles: the engine oil level is too low.
! Avoid long journeys when there is too little coolant in the cooling
system. Otherwise the engine will be damaged.
X Check the oil level when next refuelling, at the latest (Y page 334).
X If necessary, top up the engine oil (Y page 334).
If you have to top up the engine oil frequently:
X Contact a qualified specialist workshop and have the engine
checked.
Information on approved engine oils can be obtained from any quali-
fied specialist workshop or on the Internet at http://bevo.mercedes-
benz.com. 4
Engine oil level Engine oil level
Stop Stop
vehicle
vehicle Switch
Switch
engine off
engine off Mercedes-AMG vehicles: the engine oil level is too low.
There is a risk of engine damage.
X Stop the vehicle immediately, paying attention to road and traffic
conditions, and switch off the engine.
X Safeguard the vehicle against rolling away (Y page 168).
X Check the engine oil level (Y page 334).
X If necessary, top up the engine oil (Y page 334). Display messages
273On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions 8
Reserve fuel level Reserve fuel level The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated if the fuel level drops
into the reserve range.
X Refuel at the nearest filling station. C There is very little fuel in the fuel tank.
Operation of the auxiliary heating is deactivated.
X You must refuel at the nearest filling station. ¸
Replace Replace
air
air cleaner
cleaner
element
element Vehicles with a diesel engine: the engine air filter is dirty and must be
replaced.
X Consult a qualified specialist workshop. !
Clean the fuel fil‐ Clean the fuel fil‐
ter ter Vehicles with a diesel engine: there is water in the fuel filter. The water
must be drained off.
X Consult a qualified specialist workshop. Ø
Refill AdBlue See Refill AdBlue See
Owner's Manual Owner's Manual The AdBlue
®
level has fallen below the reserve range. A warning tone
also sounds.
X Have AdBlue ®
refilled as soon as possible at a qualified specialist
workshop.
or X Add at least 3.8 l of AdBlue ®
immediately (Y page 166). Ø
Refill AdBlue No Refill AdBlue No
start in .. km start in .. km The AdBlue
®
level is only sufficient for the indicated distance. A warn-
ing tone also sounds.
X Have AdBlue ®
refilled as soon as possible at a qualified specialist
workshop.
or
X Add at least 3.8 l of AdBlue ®
immediately (Y page 166). Ø
Refill AdBlue Eng. Refill AdBlue Eng.
start not possible start not possible The AdBlue
®
tank is empty. A warning tone also sounds. You can no
longer start the engine.
X Consult a qualified specialist workshop immediately.
or X Add at least 3.8 l of AdBlue ®
immediately (Y page 166). Ø
Check AdBlue See Check AdBlue See
Owner's Manual Owner's Manual The AdBlue
®
system is malfunctioning. A warning tone also sounds.
X Consult a qualified specialist workshop. 274
Display
messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions j
Check Check
trailer
trailer hitch
hitch
lock
lock The trailer tow hitch is not operational.
A warning tone also sounds.
G WARNING
If the ball coupling is not in the locked position, the trailer may come
loose. There is a risk of an accident.
X Stop the vehicle immediately, paying attention to road and traffic
conditions, and switch off the engine.
X Secure the vehicle against rolling away (Y page 168).
X Uncouple the trailer and secure it against rolling away.
X Initiate a new swivelling procedure (Y page 235).
X When the display message disappears, re-couple the trailer.
If the display message continues to be displayed: X Do not re-couple the trailer.
X Check the ground clearance and continue driving without the
trailer.
X Consult a qualified specialist workshop. j
Trailer coupling Trailer coupling
extending extending The ball coupling is swivelled out or in.
Only swivel the ball coupling in or out when the vehicle is stationary.
No trailer may be coupled during the swivelling procedure. Do not
attempt to speed up, slow down or initiate the swivelling process using your hand, foot or other aids.
X Move the ball coupling of the trailer tow hitch to an operational
position (Y page 235). &
inoperative inoperative
Battery
Battery
low
low The on-board voltage is too low.
The auxiliary heating has switched itself off or cannot be switched on
(Y page 140).
X Drive for a considerable distance.
The battery charges. The auxiliary heating is operational again as
soon as the on-board electrical system voltage is sufficient. &
inoperative Refuel inoperative Refuel
vehicle vehicle There is too little fuel in the fuel tank. The auxiliary heating cannot be
switched on (Y page 140).
X Refuel at the nearest filling station. &
inoperative inoperative
See
SeeOwn‐
Own‐
er's Man.
er's Man. The auxiliary heating is temporarily malfunctioning or faulty.
X When the vehicle is on a level surface and the engine has cooled
down, make up to four attempts to switch on the auxiliary heating,
waiting several minutes between each attempt (Y page 140).
If the auxiliary heating does not switch on: X Consult a qualified specialist workshop. 288
Display
messagesOn-board computer and displays

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions ÷
N
The yellow ESP ®
warning lamp flashes while the vehicle is in motion.
ESP ®
or traction control has engaged due to a risk of skidding or because at least
one wheel has started to spin.
Cruise control or Distance Pilot DISTRONIC is deactivated.
X Only depress the accelerator pedal as far as necessary when pulling away.
X Accelerate more gently while the vehicle is in motion.
X Adapt your driving style to suit the road and weather conditions.
X Do not deactivate ESP ®
.
In rare cases (Y page 73) it may be better to deactivate ESP ®
.
Observe the important safety notes on ESP ®
(Y page 73). å
N
The yellow ESP ®
OFF warning lamp is lit while the engine is running.
ESP ®
is deactivated.
G WARNING
If ESP ®
is deactivated, ESP ®
is unable to stabilise the vehicle.
Further driving systems or driving safety systems are thus restricted, e.g. Active
Blind Spot Assist. The system does not perform course-correcting braking appli-
cations.
There is an increased danger of skidding and risk of an accident.
X Reactivate ESP ®
.
In rare cases (Y page 73) it may be better to deactivate ESP ®
.
Observe the important safety notes on ESP ®
(Y page 73).
X Adapt your driving style to suit the road and weather conditions.
If ESP ®
cannot be activated:
X Drive on carefully.
X Contact a qualified specialist workshop immediately and have the ESP ®
system
checked. 296
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions !
N
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. 6
N
The red restraint system warning lamp is lit while the engine is running.
The restraint system is malfunctioning.
G WARNING
The airbags or belt tensioners may either be triggered unintentionally or, in the
event of an accident, may not be triggered.
This poses 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 immediately and have the restraint sys-
tem checked.
Further information about the restraint system (Y page 42).Engine
Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions ;
N
The yellow engine diagnostics warning lamp lights up while the engine is run-
ning.
A fault may exist with the following, for example:
R Engine management
R In the fuel injection system
R Exhaust system
R Ignition system (for vehicles with petrol engines)
R Fuel system
The emission limit values may be exceeded and the engine may be running in
emergency mode.
X Consult a qualified specialist workshop immediately.
Vehicles with a diesel engine: the fuel tank has been run dry (Y page 165).
X Start the engine three to four times after refuelling.
If the yellow engine diagnostics warning lamp goes out, emergency running
mode is cancelled. The vehicle does not have to be checked. 8
N
The yellow reserve fuel warning lamp is on while the engine is running.
The fuel level has dropped into the reserve range.
Operation of the auxiliary heating is deactivated if the fuel level drops into the
reserve range.
X Refuel at the nearest filling station. 298
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Warning/
indicator
lamp
N N
Signal type
Possible causes/consequences and M
M Solutions ?
N
The red coolant warning lamp comes on while the engine is running.
The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator may be blocked or the electric engine radiator fan may be malfunctioning.
The coolant is too hot and the engine is not being cooled sufficiently.
X Observe the additional display messages in the multifunction display.
X Stop the vehicle immediately, paying attention to road and traffic conditions,
and switch off the engine.
X Safeguard the vehicle against rolling away (Y page 168).
X Leave the vehicle and keep a safe distance from the vehicle until the engine has
cooled down.
X Check the coolant level and top up the coolant, observing the warning notes
(Y page 335).
X If you have to top up the coolant frequently, have the engine cooling system
checked.
X Make sure that the air supply to the engine radiator is not blocked, e.g. by frozen
slush.
X Do not start the engine again until the coolant temperature is below 120 †. The
engine may otherwise be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in mountainous terrain
and stop-start traffic. ?
N
The red coolant warning lamp comes on while the engine is running.
The coolant temperature has exceeded 120 †. The airflow to the engine radiator may be blocked or the coolant level may be too low.
G WARNING
The engine is not being cooled sufficiently and may be damaged.
Never drive with an overheated engine. Driving when your engine is overheated
can cause any fluids that may have leaked into the engine compartment to catch fire.
In addition, steam from an overheated engine can cause serious burns, which can
occur just by opening the bonnet.
There is a risk of injury.
X Observe the additional display messages in the multifunction display.
X Stop the vehicle immediately, paying attention to road and traffic conditions,
and switch off the engine.
X Safeguard the vehicle against rolling away (Y page 168).
X Leave the vehicle and keep a safe distance from the vehicle until the engine has
cooled down.
X Check the coolant level and top up the coolant, observing the warning notes
(Y page 335).
X If you have to top up the coolant frequently, have the engine cooling system
checked. 300
Warning and indicator lamps in the instrument clusterOn-board computer and displays