check engine light MERCEDES-BENZ G-CLASS 2018 Owner's Guide

Display messagesPossible causes/consequences andMSolutions
FrontPassengerAir‐bag Enable dSeeOperator' sManual
The 45indicator lamp does not remain lit if a special Baby-
Smart™-compatible child restraint system has been installed on the
front-passenger seat.
The BabySmart™ system is malfunctioning.
GWARNING
The front-passenger front air bag can be triggered unintentionally in
the event of an accident.
There is a risk of an accident.
XMake sure there is nothing between the seat cushion and the child
seat.
XCheck for correct installation of the child restraint system.
XIf the 45indicator lamps do not light up, have the Baby-
Smart™ system checked as soon as possible at a qualified special-
ist workshop.
Do not transport a child on the front-passenger seat until the air bag
deactivation system has been repaired.
RadarSensorsDirtySee Operator's Man‐ual
The radar sensor system is malfunctioning.
Possible causes are:
Rdirt on sensors
Rheavy rain or snow
Rwhen driving on inter-urban roads without traffic or infrastructure,
e.g. in desert-like areas
At least one driving system is malfunctioning or temporarily unavail-
able:
RDISTRONIC PLUS
A warning tone also sounds.
Once the cause of the problem is no longer present, the driving sys-
tems will be available again. The display message disappears.
If the display message does not disappear:
XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 122).
XSwitch off the engine.
XClean all sensors (Ypage 239).
XRestart the engine.
The display message disappears.
Display messages179
On-board computer and displays
Z

Lights
Display messagesPossible causes/consequences andMSolutions
b
Example:Check LeftLow Beam
The bulb in question is malfunctioning.
XVisit a qualified specialist workshop.
or
XCheck whether you are permitted to replace the bulb yourself
(Ypage 89).
iLED light sources: the display message for the corresponding
lamp only appears when all the LEDs in the lamp have failed.
b
Malfunction SeeOperator's Manual
The exterior lighting is malfunctioning.
XVisit a qualified specialist workshop.
b
Auto Lamp FunctionInoperative
The light sensor is defective.
XVisit a qualified specialist workshop.
b
Switch Off Lights
The lights are still switched on when you leave the vehicle. A warning
tone also sounds.
XTurn the light switch to position Ã.
Engine
Display messagesPossible causes/consequences and MSolutions
+
CheckCoolantLevelSee Operator's Man‐ual
The coolant level is too low.
XAdd coolant, observing the warning notes before doing so
(Ypage 234).
XHave the coolant system checked at a qualified specialist workshop
if the coolant needs topping up more often than usual.
?The fan motor is malfunctioning.
XIf the coolant temperature is below the Hmark, drive to the nearest
qualified specialist workshop.
XAvoid heavy loads on the engine as you do so, e.g. driving in moun-
tainous terrain and stop-start traffic.
180Display messages
On-board computer and displays

Engine
Warning/
indicator
lampNSignal type
Possible causes/consequences and M
Solutions
;NThe 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
Rin the fuel system
The emission limit values may be exceeded and the engine may be in emergency
mode.
XVisit a qualified specialist workshop immediately.
In some states, you must immediately visit a qualified specialist workshop as soon as the yellow Check Engine warning lamp lights up. This is due to the legal require-
ments in effect in these states. If in doubt, check whether such legal regulations
apply in the state in which you are currently driving.
8N The yellow reserve fuel warning lamp lights up while the engine is running.
The fuel level has dropped into the reserve range.
XRefuel at the nearest gas station.
8N 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 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 workshop.
?NThe red coolant warning lamp lights up while the engine is running and the
coolant temperature gauge is at the start of the scale.
The temperature sensor for the coolant temperature gauge is malfunctioning.
The coolant temperature is no longer being monitored. There is a risk of engine
damage if the coolant temperature is too high.
XPull over and stop the vehicle safely and switch off the engine, paying attention
to road and traffic conditions. Do not continue driving under any circumstances.
XSecure the vehicle against rolling away (Ypage 122).
XConsult a qualified specialist workshop.
Warning and indicator lamps in the instrument cluster199
On-board computer and displays
Z

The hood release lever is located in the footwell
on the left-hand side of the vehicle when viewedin the direction of travel.
XMake sure that the windshield wipers are
turned off.
XPull release lever :on the hood.
The hood is released.
XLift the hood slightly.
XPush the handle of hood catch ;in the direc-
tion of the arrow and lift the hood.
The hood is opened and held open automati-
cally 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
Do not cover up the radiator, such as with a
thermal mat or insect protection cover. Other-
wise, the values of the European on-board diag- nostics may be affected. Some of these read-
ings are required by law and must be accurate at
all times.
Engine oil
Important safety notes
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.
GWARNING
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:
Rswitch off the ignition
Rnever reach into the area where there is a
risk of danger from moving components,
such as the fan rotation area
Rremove jewelry and watches
Rkeep items of clothing and hair, for exam-
ple, away from moving parts
GWARNING
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.
Engine compartment231
Maintenance and care
Z

XMake sure that tab;is below when re-
installing cover ring :(Ypage 245).
XFor safety reasons, regularly check to ensure
that the wheel is securely fastened.
Flat tire
Preparing the vehicle
Observe the notes on changing a wheel
(Ypage 275).
XStop the vehicle on solid, non-slippery and
level ground, as far away as possible from
traffic.
XSwitch on the hazard warning lamps.
XSecure the vehicle against rolling away
(Ypage 122).
XIf possible, bring the front wheels into the
straight-ahead position.
XSwitch off the engine.
XRemove the SmartKey from the ignition lock.
The steering wheel lock stays active for as
long as the SmartKey is removed.
XMake sure that the passengers are not endan-
gered as they do so. Make sure that no one is
near the danger area while a wheel is being
changed. Anyone who is not directly assisting
in the wheel change should, for example,
stand behind the barrier.
XGet out of the vehicle. Pay attention to traffic
conditions when doing so.
XClose the driver's door.
XPlace the warning triangle a suitable distance
away (Ypage 243). Observe legal require-
ments.
Battery (vehicle)
Important safety notes
Special tools and expert knowledge are required
when working on the battery, e.g. removal and
installation. You should therefore have all work
involving the battery carried out at a qualified
specialist workshop.
GWARNING
Work carried out incorrectly on the battery
can lead, for example, to a short circuit and
thus damage the vehicle electronics. This can
lead to function restrictions applying to
safety-relevant systems, e.g. the lighting sys-
tem, the ABS (anti-lock braking system) or the
ESP
®(Electronic Stability Program). The oper-
ating safety of your vehicle may be restricted.
You could lose control of the vehicle, for
example:
Rwhen braking
Rin the event of abrupt steering maneuvers
and/or when the vehicle's speed is not
adapted to the road conditions
There is a risk of an accident.
In the event of a short circuit or a similar inci- dent, contact a qualified specialist workshop
immediately. Do not drive any further. You
should have all work involving the battery car-
ried out at a qualified specialist workshop.
For further information about ABS and ESP
®,
see (Ypage 58) and (Ypage 59).
GWARNING
Electrostatic build-up can lead to the creation of sparks, which could ignite the highly explo-
sive gases of a battery. There is a risk of an
explosion.
Before handling the battery, touch the vehicle
body to remove any existing electrostatic
build-up.
The highly flammable gas mixture forms when
charging the battery as well as when jump-start-
ing.
Always make sure that neither you nor the bat-
tery is electrostatically charged. A build-up of
electrostatic charge can be caused, for exam-
ple:
Rby wearing clothing made from synthetic
fibers
Rdue to friction between clothing and seats
Rif you push or pull the battery across the car-
pet or other synthetic materials
Rif you rub the battery with a cloth
GWARNING
During the charging process, a battery produ-
ces hydrogen gas. If a short circuit occurs or
246Battery (vehicle)
Breakdown assistance

In order for the battery to achieve the maximum
possible service life, it must always be suffi-
ciently charged.
Like other batteries, the vehicle battery may
discharge over time if you do not use the vehicle.
In this case, have the battery disconnected at a
qualified specialist workshop. You can also
charge the battery with a charger recommended
by Mercedes-Benz. Contact a qualified special-
ist workshop for further information.
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 specialist
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. due to a discharged battery, you will have
to:
Rreset the head restraints on the front seats (Ypage 76)
Rreset the function for automatically folding
the exterior mirrors in/out by folding the
mirrors out once (
Ypage 82)
Charging the battery
!
Only use battery chargers with a maximum
charging voltage of 14.8 V.
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 charge the battery using the jump-
starting connection point.
The jump-starting connection point is in the
engine compartment (
Ypage 249).
XOpen the hood.
XConnect the battery charger to the positive
terminal and ground point in the same order
as when connecting the donor battery in the
jump-starting procedure (
Ypage 249).
Keep away from fire and open flames. Do not
lean over a battery. 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 specially adapted for Mercedes-Benz vehi-
cles and tested and approved by Mercedes-
Benz is available as an accessory. It permits the
charging of the battery in its installed position.
Contact an authorized Mercedes-Benz Center
for further information and availability. Read the
battery charger's operating instructions before
charging the battery.
If the warning and indicator lamps do not light up
on the instrument cluster when temperatures
are low, it is probably because 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.
248Battery (vehicle)
Breakdown assistance

Jump starting
For the jump-starting procedure, use only the jump-starting connection point in the engine com-
partment, consisting of a positive terminal and a ground point.
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.
!Avoid repeated and lengthy starting attempts. Otherwise, the catalytic converter could be
damaged by the non-combusted fuel.
If the warning and indicator lamps do not light up on the instrument cluster when temperatures are
low, it is probably because the discharged battery has frozen. In this case, you may neither charge
the battery nor jump-start the vehicle. 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 starting249
Breakdown assistance
Z