2019 MERCEDES-BENZ GLS check engine

If the lanes are narrow, vehicles driving in the
lane beyond the lane next to your vehicle may be
indicated, especially if the vehicles are not driv-
ing in the middle of their lane. This may be the
case if there are vehicles driving at the inner
edge of their lanes.
Due to the nature of the system:
R warnings may be issued in error when driving
close to crash barriers or similar solid lane
borders.
R the warning is canceled when driving for an
extended period next to long vehicles, such as
trucks.
Warning lamp
Blind Spot Assist is not active at speeds below
approximately 20 mph (30 km/h). Vehicles in
the monitoring range are then not indicated. 0043
Warning lamp
If Blind Spot Assist is activated, warning lamp 0043
in the exterior mirrors lights up yellow at speeds
of up to 20 mph (30 km/h). At speeds above
20 mph (30 km/h), the warning lamp goes out
and Blind Spot Assist is operational.
If a vehicle is detected within the blind spot
monitoring range at speeds above 20 mph
(30 km/h), warning lamp 0043on the correspond-
ing side lights up red. This warning is always
emitted when a vehicle enters the blind spot
monitoring range from behind or from the side.
When you overtake a vehicle, the warning only
occurs if the difference in speed is less than
7 mph (12 km/h).
If you select the reverse gear, Blind Spot Assist
is not operational.
The brightness of the warning lamps is auto-
matically adapted to the brightness of the sur-
roundings. Collision warning
If a vehicle is detected in the monitoring range of
Blind Spot Assist and you switch on the corre-
sponding turn signal, a double warning tone
sounds. Red warning lamp 0043flashes. If the turn
signal remains on, detected vehicles are indica-
ted by the flashing of red warning lamp 0043.
There are no further warning tones.
Switching on Blind Spot Assist X Make sure that Blind Spot Assist is activated
in the on-board computer (Y page 239).
X Turn the SmartKey to position 0048in the igni-
tion lock.
Warning lamps 0043in the exterior mirrors light
up red for approximately 1.5 seconds and
then turn yellow.
Towing a trailer
When you attach a trailer, make sure you have
correctly established the electrical connection.
This can be accomplished by checking the trailer
lighting. In this event, Blind Spot Assist is deac-
tivated. The warning lamp lights up yellow in the
exterior mirrors and the Blind Spot Assist
Blind Spot Assist
Not Available When Towing a Trailer Not Available When Towing a Trailer
See Operator's Manual See Operator's Manual message appears in
the multifunction display.
i You can deactivate the warning lamps in the
exterior mirrors.
To do so, switch off Blind Spot Assist when:
R the SmartKey is in position 0048in the igni-
tion lock
R the engine is not running
Lane Keeping Assist General notes
0043
Lane Keeping Assist camera 208
Driving systemsDriving and parking

Visual and acoustic collision warning
If you switch on the turn signals to change lanes
and a vehicle is detected in the side monitoring range, you receive a visual and acoustic collision
warning. You then hear a double warning tone
and red warning lamp 0043flashes. If the turn sig-
nal remains on, detected vehicles are indicated
by the flashing of red warning lamp 0043. There are
no further warning tones.
Course-correcting brake application If Active Blind Spot Assist detects a risk of a lat-
eral collision in the monitoring range, a course-
correcting brake application is carried out. This is meant to assist you in avoiding a collision. G
WARNING
A course-correcting brake application cannot always prevent a collision. There is a risk of an
accident.
Always steer, brake or accelerate yourself,
especially if Active Blind Spot Assist warns
you or makes a course-correcting brake appli-
cation. Always maintain a safe distance at the sides.
If a course-correcting brake application occurs, red warning lamp 0043flashes in the exterior mir-
ror and a double warning tone sounds. In addi-
tion, a display underlining the danger of a side
collision appears in the multifunction display.
In very rare cases, the system may make an
inappropriate brake application. A course-cor-
recting brake application may be interrupted at
any time by countersteering slightly or acceler-
ating.
The course-correcting brake application is avail-
able in the speed range between 20 mph
(30 km/h) and 120 mph (200 km/h).
Either no braking application, or a course-cor-
recting brake application adapted to the driving situation occurs if:
R there are vehicles or obstacles, e.g. crash
barriers, located on both sides of your vehicle.
R a vehicle approaches you too closely at the
side.
R you have adopted a sporty driving style with
high cornering speeds.
R you clearly brake or accelerate.
R a driving safety system intervenes, e.g. ESP ®
or PRE-SAFE ®
Brake. R
ESP ®
is switched off.
R the offroad program is activated (vehicles
without the Offroad Engineering package).
R the Offroad or Offroad Plus drive program is
activated (vehicles with the Off-Road Engi-
neering package).
R the LOW RANGE offroad gear is activated
(vehicles with the Offroad Engineering pack-
age).
R a loss of tire pressure or a defective tire is
detected.
Switching on Active Blind Spot Assist
X Make sure that Active Blind Spot Assist
(Y page 239) is activated in the on-board
computer.
X Turn the SmartKey to position 0048in the igni-
tion lock.
Warning lamps 0043in the exterior mirrors light
up red for approximately 1.5 seconds and
then turn yellow.
Towing a trailer
When you attach a trailer, make sure you have
correctly established the electrical connection.
This can be accomplished by checking the trailer
lighting. Active Blind Spot Assist is then deacti-
vated. The indicator lamp lights up yellow in the
exterior mirrors and the Active Blind Spot
Active Blind Spot
Asst. Not Available When Towing a Asst. Not Available When Towing a
Trailer See Operator's Manual
Trailer See Operator's Manual message
appears in the multifunction display.
Active Lane Keeping Assist General notes
Active Lane Keeping Assist monitors the area in
front of your vehicle by means of multifunction
camera 0043at the top of the windshield. Various
different areas to the front, rear and side of your 212
Driving systemsDriving and parking

R
is affected more by strong crosswinds
R demands more sensitive steering
R has a larger turning circle
This could impair the handling characteristics.
When towing a trailer, always adjust your speed to the current road and weather conditions. Do
not exceed the maximum permissible speed for
your vehicle/trailer combination. Notes on towing a trailer
General notes !
If you have a trailer tow hitch retrofitted,
changes to the cooling system and drive train may be necessary, depending on the vehicle
type.
If you have a trailer tow hitch retrofitted,
observe the anchorage points on the chassis
frame.
R Do not exceed the legally prescribed maxi-
mum speed for vehicle/trailer combinations
in the relevant country.
This lowers the risk of an accident.
R Only install an approved trailer coupling on
your vehicle.
More information on availability and installa-
tion can be obtained at any qualified special-
ist workshop.
R The bumpers of your vehicle are not suitable
for installing detachable trailer couplings.
R Do not install hired trailer couplings or other
detachable trailer couplings on the bumpers
of your vehicle.
R If you no longer need the ball coupling,
remove it from the ball coupling recess. This
will reduce the risk of damage to the ball cou-
pling.
When towing a trailer, set the tire pressure on
the rear axle of the towing vehicle for the max-
imum load. You will find the values in the tire
pressure table in the fuel filler flap of the vehicle (Y page 371).
Please note that when towing a trailer, the fol-
lowing driving systems have limited availability
or are not available at all:
R Parking Assist PARKTRONIC (Y page 189)
R Blind Spot Assist (Y page 207)
R Active Lane Keeping Assist (Y page 212)On vehicles without level control, the height of
the ball coupling will alter according to the load
placed on the vehicle. If necessary, use a trailer
with a height-adjustable drawbar.
You will find installing dimensions and loads
under "Technical data" (Y page 392).
Driving tips Also observe the notes on pulling away with a
trailer (Y
page 143).
The maximum permissible speed for vehicle/
trailer combinations depends on the type of
trailer. Before beginning the journey, check the
trailer's documents to see what the maximum
permissible speed is for your trailer. Observe the
legally permissible maximum speed in the rele-
vant country.
For certain Mercedes-Benz vehicles, the maxi-
mum permissible rear axle load is increased
when towing a trailer. See "Technical data" to
find out whether this applies to your vehicle
(Y page 392). If you utilize any of the added
maximum rear axle load when towing a trailer,
the vehicle/trailer combination may not exceed
a maximum speed of 60 mph (100 km/h) for
reasons concerning the operating permit. This
also applies in countries in which the maximum
permissible speed for car/trailer combinations
is greater than 60 mph (100 km/h).
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
with when driving without a trailer.
Use the left-hand steering wheel paddle shifter
to shift into a lower gear in good time on long
and steep downhill gradients.
This also applies if you have activated cruise
control or Active Distance Assist 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. If you need additional
braking, depress the brake pedal repeatedly
rather than continuously.
Driving tips If the trailer swings from side to side:
X Do not accelerate.
X Do not counter-steer.
X Brake if necessary. 222
Towing a trailerDriving and parking

X
Slide bolt 0083into the hole in the ball coupling
recess and the ball coupling to the stop. X
Secure the bolt using spring cotter 0084.X
Check the ball coupling, bolt and spring cotter
for correct installation.
If the ball coupling cannot be correctly mounted,
remove the ball coupling. Under these circum-
stances, the ball coupling must not be used for
trailer towing.
Have the entire trailer tow hitch checked at a
qualified specialist workshop. Coupling up a trailer
! Do not connect the trailer's brake system (if
featured) to the hydraulic brake system of the towing vehicle, as the latter is equipped with
an anti-lock brake system. Doing so will result
in a loss of function of the brake systems of
both the vehicle and the trailer.
X Shift the transmission to position 005D.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Vehicles with AIRMATIC Package: select
normal level and the Comfortdrive program.
X Switch off the engine.
X Close the doors and tailgate.
X Couple up the trailer.
X Establish the electrical connection between
the vehicle and the trailer.
X Check that the trailer lighting system is work-
ing.
X Push the combination switch upwards/down-
wards and check whether the corresponding
turn signal on the trailer flashes.
A trailer that is connected is recognized only
when the electrical connection is established
correctly and when the lighting system is work-
ing properly. The function of other systems also depends on this, for example:
R ESP ®
R Parking Assist PARKTRONIC
R Active Parking Assist
R Parking Package with rear view camera
R Active Blind Spot Assist
R Active Lane Keeping Assist
i Vehicles with the AIRMATIC Package: if you
couple up a trailer, the vehicle always remains
at normal level. When coupling up a trailer,
please observe the following:
R If the normal level has not been set man-
ually, the vehicle is automatically lowered
to normal level. This is the case if a speed of
5 mph (8 km/h) is reached.
R The Sport drive program is not available.
These restrictions apply to all accessories
powered through a connection to the trailer
power socket of your vehicle, e.g. a bicycle
carrier.
Observe the maximum permissible trailer
dimensions (width and length). 224
Towing a trailerDriving and parking

Most U.S. states and all Canadian provinces
require by law:
R Safety chains between the towing vehicle and
the trailer. The chains should be cross-woundunder the trailer drawbar. They must be fas-
tened to the vehicle's trailer coupling, not to
the bumper or the axle.
Leave enough play in the chains to make tight
cornering possible.
R A separate brake system for certain types of
trailer.
R Safety switch for braked trailers. Check the
specific legal requirements applicable to your
state.
If the trailer becomes detached from the tow-
ing vehicle, the safety feature triggers the
trailer brakes. Towing a trailer
There are numerous legal requirements con-
cerning the towing of a trailer, e.g. speed restric-
tions. Make sure that your car/trailer combina- tion complies with the local regulations:
R in your place of residence
R in the location to which you are driving
The police and local authorities can provide reli-
able information.
Observe the following when towing a trailer:
R To gain driving experience and to become
accustomed to the new handling characteris-
tics, you should practice the following in a
traffic-free location:
- cornering
- stopping
- backing up
R Before driving, check:
- trailer tow hitch
- safety switch for braked trailers
- safety chains
- electrical connections
- lights
- wheels
R Adjust the exterior mirrors to provide an
unobstructed view of the rear section of the
trailer.
R If the trailer has electronically controlled
brakes, pull away carefully. Brake manually using the brake controller and check whether
the brakes function correctly.
R Secure any objects on the trailer to prevent
the cargo from slipping when the vehicle is in
motion.
R When you couple up a trailer, check at regular
intervals that the load is firmly secured. If the trailer is equipped with trailer lights and
brakes, check the trailer to ensure that these
are working.
R Bear in mind that the handling will be less
stable when towing a trailer than when driving
without one. Avoid sudden steering move-
ments.
R The vehicle/trailer combination is heavier,
accelerates more slowly, has a decreased
gradient climbing capability and a longer
braking distance.
It is more susceptible to side winds and
requires more careful steering.
R If possible, do not brake suddenly, but instead
depress the brake pedal moderately at first sothat the trailer can activate its brakes. Then
increase the pressure on the brake pedal.
R If the automatic transmission repeatedly
shifts between gears on uphill or downhill gra-
dients, shift to a lower gear using the left-hand
steering wheel paddle shifter.
A lower gear and lower speed reduce the risk of engine failure.
R When driving downhill, shift to a lower gear to
utilize the engine's braking effect.
Avoid continuous brake application as this
may overheat the vehicle brakes and, if instal- led, the trailer brakes.
R If the coolant temperature increases dramat-
ically while the air-conditioning system is
switched on, switch off the air-conditioning
system.
Coolant heat can also be dissipated by open-
ing the windows and switching the ventilation blower and the interior temperature to the
highest level.
R When overtaking, pay particular attention to
the extended length of your vehicle/trailer
combination.
Due to the length of the vehicle/trailer com-
bination, you require additional road space in
relation to the vehicle you are overtaking
before you can change back to the original
lane. Towing a trailer
225Driving and parking Z

Decoupling a trailer
G
WARNING
If you uncouple a trailer with the overrun
brake engaged, you could trap your hand
between the vehicle and the trailer drawbar.
There is a risk of injury.
Do not uncouple a trailer if the overrun brake is engaged. G
WARNING
Vehicles with level control:
The vehicle is lowered as soon as you discon-
nect the trailer cable. This could result in your limbs or those of other people that are
between the vehicle body and tires or under-
neath the vehicle being trapped. There is a
risk of injury.
Make sure that nobody is in the immediate
vicinity of the wheel housings or under the
vehicle when you disconnect the trailer cable.
! Do not disconnect a trailer with an engaged
overrun brake. Otherwise, your vehicle could
be damaged by the rebounding of the overrun
brake.
X Shift the transmission to position 005D.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Close the doors and tailgate.
X Apply the trailer's parking brake.
X Detach the trailer cable and decouple the
trailer.
X Switch off the engine. Permissible trailer loads and drawbar
loads
Weight specifications Maximum allowable gross mass
The gross vehicle weight of the trailer is calcu-
lated by adding the weight of the trailer to the
weight of the load and equipment on the trailer.
You will find installing dimensions and loads
under "Technical data" (Y page 392).Permissible noseweight
You will find installing dimensions and loads
under "Technical data" (Y page 392).
Loading a trailer R
When loading the trailer, make sure that nei-
ther the permissible gross weight of the trailer
nor the gross vehicle weight are exceeded.
The permissible gross vehicle weight is indi-
cated on the identification plate located on
the B-pillar on the driver's side of the vehicle.
You can find the maximum permissible values
on the type plates of your vehicle and the
trailer. When calculating how much weight
the vehicle and trailer may carry, pay atten-
tion to the respective lowest values.
R The trailer drawbar load on the ball coupling
must be added to the rear axle load to avoid
exceeding the permissible gross axle weight.
The permissible gross vehicle weight is indi-
cated on the identification plate located on
the B-pillar on the driver's side of the vehicle.
i Mercedes-Benz recommends a trailer load
where the trailer drawbar noseweight
accounts for 8 % to 15 % of the trailer's per-
missible gross weight.
i The weight of additional accessories, pas-
sengers, and cargo reduces the permissible
trailer load and drawbar load for your vehicle.
Checking the vehicle and trailer weight R
To check that the weights of the towing vehi-
cle and the trailer comply with the maximum
permissible values, have the vehicle/trailer
combination (including the driver, passen-
gers, and cargo with a fully laden trailer)
weighed on a calibrated weighbridge.
R Check the gross axle weight rating of the front
and rear axles, the gross weight of the trailer
and the trailer drawbar noseweight. Removing the ball coupling
X Remove the spring cotter.
X Remove the bolt from the ball coupling
recess.
X Remove the ball coupling from the ball cou-
pling recess. 226
Towing a trailerDriving and pa
rking

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