check engine light MERCEDES-BENZ GLS 2019 Owner's Manual

Important safety notes
G
WARNING
If you operate information systems and com-
munication equipment integrated in the vehi- cle when driving, you may be distracted from
the traffic situation. You could also lose con-
trol of the vehicle. There is a risk of an acci-
dent.
Only operate this equipment when the traffic
situation permits. If you are not sure that this
is possible, park the vehicle paying attention
to traffic conditions and operate the equip-
ment when the vehicle 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 recognize function
restrictions in systems 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, pull over as soon as it is safe to do so.
Contact a qualified specialist workshop.
The on-board computer only shows messages or warnings from certain systems in the multifunc-tion display. You should therefore make sure
your vehicle is operating safely at all times.
For an overview, see the instrument panel illus-
tration (Y page 37). 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 37). X
Turn the brightness control knob clockwise or
counter-clockwise.
If you turn the light switch to 0058,0060or
0058, 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 171):
The segments light up from the stored speed to the maximum speed.
R Active Distance Assist DISTRONIC activated
(Y page 172):
One or two segments in the set speed range
light up.
R Active Distance Assist 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. Tachometer
! Do not drive in the overrevving range, as this
could damage the engine.
The red band in the tachometer 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.
Bear in mind that the outside temperature dis-
play indicates the temperature measured and
does not record the road temperature.
The outside temperature display is in the multi-
function display (Y page 232).230
Displays and operationOn-board computer and displays

Display messages
Possible causes/consequences and
0050
0050Solutions The yellow
0024warning lamp lights up and the red 0049(USA only)
or 0024 (Canada only) indicator lamp flashes.
It is not possible to apply the electric parking brake manually.
X Shift the transmission to position 005D.
X Visit a qualified specialist workshop. 0027
(USA only)
004D (Canada only)
Check Brake Fluid Check Brake Fluid
Level Level There is not enough brake fluid in the brake fluid reservoir. In addition,
the 0027 (USA only) or 004D(Canada only) warning lamp lights up in
the instrument cluster and a warning tone sounds.
G WARNING
The braking effect may be impaired.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away (Y page 158).
X Consult a qualified specialist workshop.
X Do not add brake fluid. This does not correct the malfunction. 0026
Check Check
Brake
BrakePad
PadWear
Wear The brake pads/linings have reached their wear limit.
USA only: the red
0027brake system warning lamp is lit while the
engine is running.
X Visit a qualified specialist workshop. 0053
Inoperative Inoperative One or more main features of the mbrace system are malfunctioning.
X Visit a qualified specialist workshop. Active
Active
Brake
BrakeAssist
Assist
Functions
Functions Currently
Currently
Limited See Opera‐
Limited See Opera‐
tor's Manual tor's Manual Active Brake Assist with cross-traffic function is temporarily inopera-
tive.
Possible causes are:
R the radar sensor system is temporarily inoperative, e.g. due to elec-
tromagnetic radiation emitted by nearby TV or radio stations or
other sources of electromagnetic radiation
R the system is outside the operating temperature range
R the on-board voltage is too low
When the causes stated above no longer apply, the display message
disappears.
Active Brake Assist with cross-traffic function or PRE ‑SAFE®
PLUS is
functional again.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 158).
X Restart the engine. Display
messages
251On-board computer and displays Z

Display messages
Possible causes/consequences and
0050
0050Solutions 0049
Switch Off Lights Switch Off Lights You leave the vehicle and the lights are switched on. A warning tone
also sounds.
X Turn the light switch to the 0058position. 0049
Switch On Headlamps Switch On Headlamps You are driving with low-beam headlamps switched off.
X Turn the light switch to the 0058or0058 position. Adaptive Highbeam
Adaptive Highbeam
Assist Currently Assist Currently
Unavailable See Unavailable See
Operator's Manual Operator's Manual Adaptive Highbeam Assist is deactivated and temporarily inoperative.
Possible causes are:
R the windshield in the camera's field of vision is dirty
R visibility is impaired due to heavy rain, snow or fog
X Clean the windshield.
If the system detects that the camera is fully operational, the Adap‐
Adap‐
tive Highbeam Assist Now Available
tive Highbeam Assist Now Available message is displayed.
Adaptive Highbeam Assist is operational again. Adaptive Highbeam
Adaptive Highbeam
Assist Inoperative
Assist Inoperative Adaptive Highbeam Assist is faulty.
X
Visit a qualified specialist workshop. Engine
Display messages
Possible causes/consequences and
0050 0050Solutions 00BD
Check Check
Coolant
Coolant Level Level
See Operator's Man‐
See Operator's Man‐
ual ual The coolant level is too low.
! Avoid longer journeys when there is insufficient coolant in the
engine cooling system. You could otherwise damage the engine.
X Add coolant, observing the warning notes before doing so
(Y page 324).
If you have to add coolant frequently:
X Contact a qualified specialist workshop and have the engine cooling
system checked. 00AC The fan motor is defective.
X At coolant temperatures below 248 ‡(120 †), drive 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-and-go traffic. 258
Display messagesOn-board computer and displays

Warning/
indicator
lamp
0051
0051 Signal type
Possible causes/consequences and 0050 0050Solutions 00490024
0051
0049 (USA only), 0024(Canada only): 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. 0075
0051
The red restraint system warning lamp is lit while the engine is running.
The restraint system is malfunctioning.
G WARNING
The air bags or Emergency Tensioning Devices may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
There is 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 and have the restraint system checked.
For further information about the restraint system, see (Y page 44).Engine
Warning/
indicator
lamp
0051
0051 Signal type
Possible causes/consequences and 0050 0050Solutions 00B9
0051
The yellow Check Engine warning lamp lights up while the engine is running.
There may be a malfunction, for example:
R in the engine management
R in the fuel injection system
R in the exhaust system
R in the ignition system (for vehicles with gasoline engines)
R in the fuel system
The emission limit values may be exceeded and the engine may be in emergency mode.
X Visit 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. 00B6
0051
The yellow reserve fuel warning lamp lights up while the engine is running.
The fuel level has dropped into the reserve range.
X Refuel at the nearest gas station. 282
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Warning/
indicator
lamp
0051 0051
Signal type
Possible causes/consequences and 0050
0050Solutions 00B6
0051
The yellow reserve fuel warning lamp flashes while the vehicle is in motion.
In addition, the 00B9Check Engine warning lamp may light up.
The fuel filler cap is not closed correctly or the fuel system is leaking.
X Check that the fuel filler cap is correctly closed.
X If the fuel filler cap is not correctly closed: close the fuel filler cap.
X If the fuel filler cap is closed: visit a qualified specialist workshop.00AC
0051
The red coolant warning lamp lights up while the engine is running and the
coolant temperature gage is at the start of the scale.
The temperature sensor for the coolant temperature gage is malfunctioning.
The coolant temperature is no longer being monitored. There is a risk of engine
damage if the coolant temperature is too high.
X Pull 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.
X Secure the vehicle against rolling away (Y page 158).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
283On-board computer and displays Z

X
Make sure that the windshield wipers are
turned off.
X Pull release lever 0043on the hood.
The hood is released. X
Reach into the gap, pull hood catch handle 0044
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
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 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
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
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. 322
Engine compartmentMaintenance and care

X
Make sure that the vehicle is stationary and
the SmartKey is in position 0048in the ignition
lock.
X Open the camera cover for cleaning via the
multimedia system (see Digital Operator's
Manual).
X To clean the camera: use clean water and a
soft cloth to clean the camera lens 0043.
360° camera: if you drive at speeds above
20 mph (30 km/h) or with the SmartKey in posi- tion 0092or0047 in the ignition lock, the cover of
the 360° camera closes.
Cleaning the exhaust pipe G
WARNING
The exhaust tail pipe and tail pipe trim can
become very hot. If you come into contact
with these parts of the vehicle, you could burn
yourself. There is a risk of burns.
Always be particularly careful and supervise
children closely around the exhaust pipe and
the exhaust pipe trims. Allow these compo-
nents to cool down before touching them.
! Vehicles with black exhaust pipes: black
chromed screens should not be polished with a chrome polish. They will otherwise lose their
black shine. For optimal care, the screens
should be rubbed with a lightly oiled cloth
after every car wash. Commercially available
engine and care oils are suitable for this.
For heavier soiling, you can apply a fine paint- work polish with a microfiber cloth. Remove
the excess polish residue after polishing.
Impurities combined with the effects of road grit
and corrosive environmental factors may cause flash rust to form on the surface. You can
restore the original shine of the exhaust pipe by
cleaning it regularly, especially in winter and
after washing.
X Clean the exhaust pipe with a chrome care
product tested and approved by Mercedes-
Benz.
Cleaning the trailer tow hitch H
Environmental note
Dispose of rags soaked in oil and grease in an environmentally responsible manner. !
Do not clean the ball coupling with a power
washer. Do not use solvents.
! Please note the care instructions in the
trailer coupling manufacturer's operating
instructions. The ball coupling must be cleaned if it becomes
dirty or corroded.
X Remove rust on the ball of the ball coupling,
e.g. with a wire brush.
X Remove dirt with a clean, lint-free cloth or a
brush.
X After cleaning, lightly oil or grease ball cou-
pling 0043.
X Check that the vehicle's trailer tow hitch is
working properly.
i You can also have the maintenance work on
the ball coupling and the trailer tow hitch car-
ried out by a qualified specialist workshop. Interior care
Cleaning the display !
For cleaning, do not use any of the following:
R alcohol-based thinner or gasoline
R abrasive cleaning agents
R commercially-available household cleaning
agents
These may damage the display surface. Do
not put pressure on the display surface when
cleaning. This could lead to irreparable dam-
age to the display. Care
331Maintenance and care Z

occupants from suffering acid burns should the
battery be damaged in the event of an accident.
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. However, you can also charge the battery with a charger recom-
mended by Mercedes-Benz. Contact a qualified
specialist workshop for further information.
Have the battery charge state checked more
frequently if you use the vehicle mainly for short trips or if you leave it standing idle for a lengthyperiod. 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.
If the power supply has been interrupted, e.g. if
you reconnect the battery, you will have to:
R set the clock (see the Digital Operator's Man-
ual)
On vehicles with a multimedia system and
navigation system, the clock is set automati-
cally.
R reset the function for automatically folding
the exterior mirrors in/out by folding the mir-
rors out once(Y page 111) Charging the 12 V battery
G
WARNING
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. G
WARNING
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. G
WARNING
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 maximum
charging voltage of 14.8 V.
! Only charge the battery using the jump-
starting connection point.
The jump-starting connection point is in the
engine compartment (Y page 343).
X Open the hood.
X Connect 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 (Y page 343).
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, at low temperatures, the indicator lamps/
warning lamps in the instrument cluster do not
light up, it is highly 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. 342
Battery (vehicle)Breakdown assistance

G
WARNING
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. Otherwise, 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 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 characteristics can be
impaired, particularly at low temperatures. Have the thawed-out battery checked at a qualified
specialist workshop.
Do not start the vehicle using a rapid charging device. If your vehicle's battery is discharged, the
engine can be jump-started from another vehicle or from a donor battery using jumper cables.
Observe the following points:
R The battery is not accessible in all vehicles. If the other vehicle's battery is not accessible, jump-
start the vehicle using a donor battery or a jump-starting device.
R Vehicles with a gasoline engine: only jump-start the vehicle when the engine and exhaust
system are cold.
R Do not start the engine if the battery is frozen. Let the battery thaw first.
R Only jump-start from batteries with a 12 V voltage rating.
R Only use jumper cables which have a sufficient cross-section and insulated terminal clamps.
R If the battery is fully discharged, leave the battery that is being used to jump-start connected for
a few minutes before attempting to start. This charges the battery slightly.
R Make sure that the two vehicles do not touch.
Make sure that:
R The jumper cables are not damaged.
R Bare parts of the terminal clamp do not come into contact with other metal parts while the jumper
cables are connected to the battery.
R The jumper cables cannot come into contact with parts that can move when the engine is running,
such as the V-belt pulley or the fan.
X Secure the vehicle by applying the electric parking brake.
X Shift the transmission to position 005D.
X Make sure that the ignition is switched off. All indicator lamps in the instrument cluster must be
off. When using the SmartKey, turn the SmartKey to position 0092in the ignition lock and remove it
(Y page 140).
X Switch off all electrical consumers, e.g. rear window defroster, lighting, etc.
X Open the hood.
i Right-hand-drive vehicle:
the jump-starting connection points may be located on the other
side of the vehicle. 344
Jump-startingBreakdown assistance