check engine MERCEDES-BENZ GL-Class 2014 X166 Service Manual

Display messages Possible causes/consequences and
M
MSolutions 8
Ultra Low-sulfur Ultra Low-sulfur
Diesel Fuel Only Diesel Fuel Only Vehicles with a diesel engine: the fuel level has fallen below the
reserve range.
X
Refuel at the nearest gas station.
X Only use commercially available vehicular ULTRA-LOW SULFUR
HIGHWAY DIESEL FUEL (ULSD, 15 ppm sulfur MAXIMUM). ¸
Replace Air Filter Replace Air Filter Vehicles with a diesel engine: the engine air filter is dirty and must
be replaced.
X
Visit a qualified specialist workshop. !
Check Fuel Filter Check Fuel Filter Vehicles with a diesel engine: there is water in the fuel filter. The
water must be drained off.
X
Visit a qualified specialist workshop. Ø
Check Check
Additive
Additive See
See
Operator's Manual
Operator's Manual The DEF tank is almost empty.
X
Have the DEF tank filled as soon as possible at a qualified
specialist workshop (Y page 186).Ø
Remaining Starts: Remaining Starts:
16 16 The DEF level has fallen to a minimum. You can start the engine a
further 16 times.
X
Have the DEF tank filled immediately at a qualified specialist
workshop (Y page 186).
i You can start the engine a further 16 times. If DEF is not added,
it will then not be possible to restart the engine. Refill the DEF
tank with approximately 1 gal (3.8 l) DEF (Y page 186).Driving systems
Display messages Possible causes/consequences and
M MSolutions À
Attention Assist: Attention Assist:
Take a Break! Take a Break! Based on certain criteria, ATTENTION ASSIST has detected fatigue
or a lack of concentration on the part of the driver. A warning tone
also sounds.
X
If necessary, take a break.
During long journeys, take regular breaks in good time so you get
enough rest. À
Attention Assist Attention Assist
Inoperative Inoperative ATTENTION ASSIST is inoperative.
X
Visit a qualified specialist workshop. Display
messages
309On-board computer and displays Z

Display messages Possible causes/consequences and
M
MSolutions LOW RANGE Stop
LOW RANGE Stop
Apply Apply
Parking
Parking Brake
Brake A gearshift process has been canceled. LOW RANGE is in the
neutral position. There is no connection between the engine and
the drive wheels.
X
Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Apply the electric parking brake. Do not continue driving under
any circumstances.
X Repeat the gearshift process. LOW RANGE LOW RANGE
Malfunction To Malfunction To
Park, Apply Brake Park, Apply Brake LOW RANGE is malfunctioning.
X
Do not drive at speeds above 50 mph (80 km/h).
X When parking, secure the vehicle against rolling away
(Y page 188).
X Have the vehicle checked at a qualified specialist workshop. LOW RANGE LOW RANGE
Max.Speed 25 mph Max.Speed 25 mph You have exceeded the maximum speed for the gearshift process.
X
Drive more slowly.
The gear change is made. LOW RANGE Max. LOW RANGE Max.
Speed 40 mph Speed 40 mph You have exceeded the maximum speed for the gearshift process.
X
Drive more slowly.
The gear change is made. LOW LOW
RANGE
RANGE Shift
Shiftto
to
Position N Briefly
Position N Briefly You have reduced the vehicle speed, but the automatic
transmission is not in position
N.
X Briefly shift the automatic transmission to position N.LOW LOW
RANGE
RANGE Shifting
Shifting
Canceled Please
Canceled Please
Reactivate Reactivate The gearshift process has been canceled.
X
Repeat the gearshift process. Ã
Inoperative Inoperative DSR (Downhill Speed Regulation) is deactivated due to a
malfunction.
X
Have DSR checked at a qualified specialist workshop. ë
Off Off The HOLD function is deactivated. the vehicle is skidding.
A warning tone also sounds.
X
Reactivate the HOLD function later (Y page 216).Radar Sensors Radar Sensors
Deactivated See Deactivated See
Operator's Manual Operator's Manual The radar sensor system is deactivated.
X
Switch on the radar sensor system (Y page 285).312
Display
messagesOn-board computer and displays

Display messages Possible causes/consequences and
M
MSolutions DISTRONIC PLUS
DISTRONIC PLUS
Currently Currently
Unavailable See Unavailable See
Operator's Manual Operator's Manual DISTRONIC PLUS is temporarily inoperative. Possible causes are:
R
function is impaired due to heavy rain or snow.
R the sensors in the radiator grill and the bumper are dirty.
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic 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.
A warning tone also sounds.
When the causes stated above no longer apply, the display
message disappears.
DISTRONIC is operational 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 ( Ypage 188).
X Clean the sensors in the radiator grill and the bumper
(Y page 380).
X Restart the engine. DISTRONIC PLUS DISTRONIC PLUS
Inoperative Inoperative DISTRONIC PLUS is defective.
BAS PLUS (Brake Assist PLUS) and PRE-SAFE
®
Brake may be
inoperative as well.
A warning tone also sounds.
X Visit a qualified specialist workshop. DISTRONIC PLUS DISTRONIC PLUS
Passive Passive You have depressed the accelerator pedal. DISTRONIC PLUS is no
longer controlling the speed of the vehicle.
X
Remove your foot from the accelerator pedal. DISTRONIC PLUS DISTRONIC PLUS
- - - mph - - - mph An activation condition for DISTRONIC PLUS is not fulfilled.
X
Check the activation conditions for DISTRONIC PLUS
(Y page 203). 316
Display
messagesOn-board computer and displays

Problem Possible causes/consequences and
M
MSolutions ÷
The yellow ESP
®
warning lamp flashes
while the vehicle is in
motion. ESP
®
or traction control has intervened because there is a risk of
skidding or at least one wheel has started to spin.
Cruise control or DISTRONIC PLUS is deactivated.
X When pulling away, only depress the accelerator pedal as far as
necessary.
X Ease off the accelerator pedal 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 72), it may be best to deactivate ESP ®
. å
The yellow ESP
®
OFF
warning lamp is lit while
the engine is running. ESP
®
is deactivated.
G WARNING
If ESP ®
is switched off, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Reactivate ESP ®
.
In rare cases (Y page 72), it may be best to deactivate ESP ®
.
X Adapt your driving style to suit the road and weather conditions.
If ESP ®
cannot be activated:
X Have ESP ®
checked at a qualified specialist workshop. ֌
The yellow ESP
®
and
ESP ®
OFF warning
lamps are lit while the
engine is running. ESP
®
, BAS, BAS PLUS, PRE-SAFE ®
, PRE-SAFE ®
Brake, COLLISION
PREVENTION ASSIST, the HOLD function, hill start assist,
crosswind driving assistance and ESP ®
trailer stabilization are not
available due to a malfunction.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above.
The braking distance in an emergency braking situation can thus
increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Observe the additional display messages in the multifunction
display.
X Drive on carefully.
X Visit a qualified specialist workshop. 330
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Problem Possible causes/consequences and
M
MSolutions F
(USA only)
! (Canada only)
The red electric parking
brake indicator lamp
flashes or lights up
and/or
!
warning lamp for the
electric parking brake
lights up. X
Observe the additional display messages in the multifunction
display. 6
The red SRS warning
lamp is lit while the
engine is running.
There is a malfunction in the SRS (Supplemental Restraint
System).
G WARNING
The air bags or Emergency Tensioning Devices may either be
triggered unintentionally 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 Have SRS checked at a qualified specialist workshop
immediately.
For further information about SRS, see (Y page 43).332
Warning and indicator lamps in the instrument clusterOn-board computer and displays

Engine
Problem Possible causes/consequences and
M
MSolutions ;
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 Have the vehicle checked as soon as possible at a qualified
specialist workshop.
i 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 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
(Y
page 185).
X Start 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
running.
The fuel level has dropped into the reserve range.
X
Refuel 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.
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. Warning and indicator lamps in the instrument cluster
333On-board computer and displays Z

Problem Possible causes/consequences and
M
MSolutions ?
The red coolant
warning lamp comes on
while the engine is
running.
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.
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 no longer being cooled
sufficiently.
X Observe the additional display messages in the multifunction
display.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 188).
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and add coolant, observing the warning
notes (Y page 373).
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X Do not start the engine again until the coolant temperature is
below 248 ‡(120 †). Otherwise, the engine could be damaged.
X Drive to the nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic. ?
The red coolant
warning lamp comes on
while the engine is
running. A warning tone
also sounds.
The coolant temperature has exceeded 248 ‡ (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.
Do not drive when your engine is overheated. This can cause some
fluids which may have leaked into the engine compartment to
catch fire.
Steam from the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury. Warning and indicator lamps in the instrument cluster
335On-board computer and displays Z

Problem Possible causes/consequences and
M
MSolutions X
Observe the additional display messages in the multifunction
display.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 188).
X Leave the vehicle and keep a safe distance from the vehicle until
the engine has cooled down.
X Check the coolant level and add coolant, observing the warning
notes (Y page 373).
X If you need to add coolant more often than usual, have the
engine coolant system checked.
X Make sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.
X At coolant temperatures below 248 ‡ (120 †), drive to the
nearest qualified specialist workshop.
X Avoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic. Driving systems
Problem Possible causes/consequences and
M MSolutions ·
The red distance
warning function
warning lamp comes on
while the vehicle is
moving. A warning tone
also sounds.
You are approaching a vehicle or a stationary obstacle in your line
of travel at too high a speed.
X
Be prepared to brake immediately.
X Pay careful attention to the traffic situation. You may have to
brake or take evasive action.
Further information on DISTRONIC PLUS (Y page 203).
Further information on PRE-SAFE ®
Brake (Y page 75).
Further information on the distance warning function
(Y page 69). 336
Warning and indicator lamps in the instrument clusterOn-board computer and displays

the on-board voltage is too low, the power
to the sockets is automatically cut. This
ensures that there is sufficient power to
start the engine.
Socket in the front-compartment center
console !
The socket is not suitable for operating
the tire inflation compressor. X
To open: slide cover :to its foremost
position.
X Lift up the cover of socket ;.
X To close: pull cover :back as far as it will
go.
Socket in the rear-compartment center
console X
Lift up the cover of socket :.
Vehicles with the Rear Seat Entertainment
System have two sockets in the center
console in the rear compartment. Socket in the cargo compartment
X
Lift up the cover of socket :. 115 V socket
Important safety notes G
DANGER
When a suitable device is connected, the
115 V power socket will be carrying a high
voltage. You could receive an electric shock
if the connector cable or the 115 V power
socket is pulled out of the trim or is damaged
or wet. There is a risk of fatal injury.
R Use only connector cables that are dry and
free of damage.
R When the ignition is off, make sure that the
115 V power socket is dry.
R Have the 115 V power socket checked or
replaced immediately at a qualified
specialized workshop if it is damaged or has
been pulled out of the trim.
R Never plug the connector cable into a
115 V power socket that is damaged or has
been pulled out of the trim. G
DANGER
If you reach into the power socket or plug
inappropriate devices into the power socket,
you could receive an electric shock. There is
a risk of fatal injury.
Only connect appropriate devices to the
power socket. Features
353Stowage an d features Z

!
Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield
wipers or the hood. X
Make sure that the windshield wipers are
turned off.
X Pull release lever :on the hood.
The hood is released. X
Reach into the gap, pull hood catch
handle ;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
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-
diagnostic 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:
R
park the vehicle on a level surface.
R the engine should be switched off for
approximately five minutes if the engine is
at normal operating temperature.
R if 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
dipstick G
WARNING
Certain components in the engine
compartment, 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 compartment
371Maintenance and care Z