check engine light MERCEDES-BENZ GL-Class 2016 X166 Owner's Guide

using the brake controller and check
whether the brakes function correctly.
RSecure any objects on the trailer to prevent
the cargo from slipping when the vehicle is
in motion.
RWhen you couple up a trailer, check at reg-
ular intervals that the load isfirmly secured.
If the trailer isequipped with trailer lights
and brakes, check the trailer to ensure that
these are working.
RBear inmind that the handlin g will be less
stable when towing a trailer than when driv-
ing without one. Avoid sudden steering
movements.
RThe vehicle/trailer combination isheavier,
accelerates more slowly, has a decreased
gradient cli mbing capability and a longer
braking distance.
It is more susceptible to side winds and
requires more careful steering.
RIf possible, do not brake suddenly, but
instead depress the brake pedal moder-
ate lyat first so that the trailer can activate
it s brakes. Then increase the pressure on
the brake pedal.
RIf the automat ictransmission repeatedly
shifts between gears on uphill or downhill
gradients, shift to a lower gear using the
left-hand steering wheel paddleshifter.
A lower gear and lower speed reduce the
risk of engine failure.
RWhen drivingdown hill, shift to a lower gear
to uti lize the engine's braking effect.
Avoid co ntin
uous brake application as this
may overheat the vehicle brakes and, if
instal led,the trailer brakes.
RIfthe coolant temperature increases dra-
matical ly while the air-cond itioning system
is swit ched on, switch off the air-condition-
ing system.
Coolant heat can also bedissipated by
opening the windows and switching the ventilation
blower and the interior temper-
ature to the highest leve l.
RWhen overtaking, pay particular attention
to the extended length of your vehicle/
trailer combination.
Due to the length of the vehicle/trailer
combination, you require additional road
spaceinrelation to the vehicle you are
overtaking before you can change back to
the original lane.
Decoupling a trailer
GWARNIN G
If you uncouple atrailer wit hth eoverrun
brak eengaged ,you could trap your han d
between th evehicl eand th etrailer drawbar.
Ther eis aris kof injury.
Do no tuncouple atrailer if th eoverrun brak e
is engaged .
GWARNING
Vehicles wit hleve lcontrol :
The vehicl eis lowered as soo nas you discon -
nect th etrailer cable. This could result in your
limb sor those of other people that are
between th evehicl ebody and tires or under-
neath th evehicl ebein gtrapped .Ther eis a
ris kof injury.
Mak esure that nobody is in th eimmediat e
vicinity of th ewhee lhousing sor under th e
vehicl ewhen you disconnect th etrailer cable.
!Do not disconnect a trailer with an
engaged overrun brake. Otherwise, your
vehicle could bedamaged bythe rebound-
ing of the overrun brake.
XSh ift the transmission to position P.
XApply the vehicle's electr icparking brake.
XStart the engine.
XClose the doors and tailgate.
XApply the trailer's parking brake.
268Towing a trailer
Driving and parking

Display messagesPossible causes/consequences andMSolutions
b
AUTOlightsinoper ‐
ative
The ligh tsensor is defective.
XVisit aqualified specialist workshop .
b
Switch off lights
You leaveth evehicl eand th eligh tis still switched on . Awarnin g
tone also sounds.
XTur nth eligh tswitch to th eà position .
Adaptive Highbeam
Assist Currently
Unavailable See
Operator' sManual
Adaptive Highbeam Assis tis deactivated and temporarily inoper -
ative. Possibl ecauses are:
Rth ewindshield in th ecamera' sfield of vision is dirty.
Rvisibility is impaire ddue to heav yrain ,snow or fog.
XClean th ewindshield.
If th esystem detects that th ecamera is full yoperational again ,th e
Adaptive Highbeam Assist Now Available
message is dis-
played .
Adaptive Highbeam Assis tis operational again .
Adaptive Highbeam
Assist Inoperative
Adaptive Highbeam Assis tis faulty.
XVisit aqualified specialist workshop .
Engine
Display messagesPossible causes/consequences and MSolutions
+
Check Coolant
Level See Opera‐
tor's Manual
The coolantlevel is to olow.
!Avoid makin glon gjourneys wit hto olittl ecoolan tin th eengin e
coolin gsystem. The engin ewill otherwise be damaged.
XAd dcoolant, observin gth ewarnin gnote sbefore doin gso
(
Ypage 373).
XIf you need to add coolan tmor eofte nthan usual, hav eth e
engin ecoolan tsystem checke dat aqualified specialist work-
shop.
?The fan motor is faulty.
XAt coolan ttemperatures belo w24 8 ‡ (120†), drive to th e
neares tqualified specialist workshop .
XAvoid subjecting theengin eto heav yloads ,e.g. drivin gin moun-
tainous terrain ,and stop-and-g otraffic.
306Display messages
On-board computer and displays

ProblemPossible causes/consequences andMSolutions
F(USA only)
The red electric parking
brake indicator lamp
flashes or lights up
and/or
!
the yellow warning
lamp for the electric
parking brake lights up.XObserve the additional display messages in the multifunction
display.
6
The red restraint sys-
tem warning lamp is lit
while the engine is run-
ning.The restraint system is faulty.
GWARNING
The air bags or Emergency Tensioning Devices may either be trig-
gered unintentionally or, in the event of an accident, may not be
triggered.
There is an increased risk of injury.
XObserve the additional display messages in the multifunction
display.
XDrive on carefully.
XHave the restraint system checked immediately at a qualified
specialist workshop.
For further information about the restraint system, see
(
Ypage 44).
Warning and indicator lamps in the instrument cluster333
On-board computer and displays
Z

Engine
ProblemPossible causes/consequences andMSolutions
;
The yellow Check
Engine warning lamp
lights up while the
engine is running.There may be a malfunction, for example:
Rin the engine management
Rin the fuel injection system
Rin the exhaust system
Rin the ignition system (for vehicles with gasoline engines)
Rin the fuel system
The emission limit values may be exceeded and the engine may be
in emergency mode.
XHave the vehicle checked as soon as possible at a qualified
specialist workshop.
iIn some states, you must immediately visit a qualified special-
ist workshop as soon as the yellow Check Engine warning lamp
lights up. This is due to the legal requirements in effect in these
states. If in doubt, check whether such legal regulations apply in the state in which you are currently driving.
Vehicles with a diesel engine: the fuel tank has been run dry
(
Ypage 185).
XStart the engine three to four times after refueling.
If the yellow Check Engine warning lamp goes out, emergency
running mode is canceled. The vehicle need not be checked.
8
The yellow reserve fuel
warning lamp lights up
while the engine is run-
ning.The fuel level has dropped into the reserve range.
XRefuel at the nearest gas station.
8
The yellow reserve fuel
warning lamp flashes
while the vehicle is in
motion.
In addition, the ;
Check Engine warning
lamp may light up.The fuel system pressure is too low. The fuel filler cap is not closed
correctly or the fuel system is leaking.
XCheck that the fuel filler cap is correctly closed.
XIf the fuel filler cap is not correctly closed: close the fuel filler
cap.
XIf the fuel filler cap is closed: visit a qualified specialist work-
shop.
334Warning and indicator lamps in the instrument cluster
On-board computer and displays

!Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield
wipers or the hood.
XMake sure that the windshield wipers are
turned off.
XPull release lever :on the hood.
The hood is released.
XReach into the gap, pull hood catch han-
dle ;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
XLower the hood and let it fall from a height
of approximately 8 in (20 cm).
XCheck 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
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:
Rpark the vehicle on a level surface.
Rthe engine should be switched off for
approximately five minutes if the engine is
at normal operating temperature.
Rif the engine is not at normal operating
temperature, e.g. if the engine was only
started briefly, wait about 30 minutes
before carrying out the measurement.
Checking the oil level using the oil dip-
stick
GWARNING
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.
Engine compartment371
Maintenance and care
Z

qualified specialist workshop for further infor-
mation.
Have the battery condition of charge checked
more frequently if you use the vehicle mainly
for short trips or if you leave it standing idle
for a lengthy period. Consult a qualified spe-
cialist 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.
iIf the power supply has been interrupted,
e.g. if you reconnect the battery, you will
have to:
Rset the clock. Information on setting the
clock can be found in the Digital Opera-
tor's Manual.
On vehicles with COMAND and a naviga-
tion system, the clock is set automati-
cally.
Rreset the function for folding the exterior mirrors in/out automatically, by folding
the mirrors out once (
Ypage 125).
Charging the battery
GWARNING
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.
GWARNING
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.
GWARNING
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 maxi-
mum charging voltage of 14.8 V.
!Only charge the battery using the jump-
starting connection point.
If, at low temperatures, the indicator lamps/
warning lamps in the instrument cluster do
not light up, it is highly 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 charac-
teristics can be impaired, particularly at low
temperatures. Have the thawed-out battery
checked at a qualified specialist workshop.
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 spe-
cially adapted for Mercedes-Benz vehicles
and tested and approved by Mercedes-Benz
is available as an accessory. It permits the
charging of the battery in its installed posi-
tion. Contact an authorized Mercedes-Benz
Center for further information and availabil-
ity. Charge the battery in accordance with the
separate instructions for the battery charger.
The jump-starting connection point is in the
engine compartment (
Ypage 395).
Read the battery charger's operating instruc-
tions before charging the battery.
XOpen the hood.
XConnect the battery charger to the positive terminal and ground point in the same
order as when connecting the donor bat-
tery in the jump-starting procedure
(
Ypage 395).
394Battery (vehicle)
Breakdown assistance

Jump-starting
For the jump-starting procedure, use only the jump-starting connection point, consisting of a
positive terminal and a ground point, in the engine compartment.
GWARNING
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 batteries. Wash away battery acid immediately with plenty of
clean water and seek medical attention.
GWARNING
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 ven-
tilation while charging and jump-starting. Do not lean over a battery.
GWARNING
During the charging process, a battery produces hydrogen gas. If a short circuit occurs or sparks
are created, the hydrogen gas can ignite. There is a risk of an explosion.
RMake sure that the positive terminal of a connected battery does not come into contact with
vehicle parts.
RNever place metal objects or tools on a battery.
RIt is important that you observe the described order of the battery terminals when connecting
and disconnecting a battery.
RWhen jump-starting, make sure that the battery poles with identical polarity are connected.
RIt is particularly important to observe the described order when connecting and disconnecting
the jumper cables.
RNever connect or disconnect the battery terminals while the engine is running.
GWARNING
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. Other-
wise, 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
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.
Jump-starting395
Breakdown assistance
Z