check engine MERCEDES-BENZ M-Class 2014 W166 Owner's Guide

R
Do not jump with the vehicle as this will
interrupt the vehicle's propulsion.
R Always keep the engine running and in gear
when driving on a slope.
R Do not shift the automatic transmission to
transmission position N.
i Do not use the HOLD function when
driving off-road, on steep uphill or downhill
gradients or on slippery or loose surfaces.
The HOLD functio ncannot hold the vehicle
on such surfaces.
Checklist before driving off-road !
If the engine oil warning lamp lights up
while the vehicle is in motion, stop the
vehicle in a safe place as soon as possible.
Chec kthe engine oil level. The engine oil
warning lamp warning must not be ignored.
Continuing the journey while the symbol is
displayed could lead to engine damage.
X Engine oil level: check the engine oil level
and add oil if necessary.
When driving on steep gradients, the
engine oil level must be sufficiently high to
ensure a correct oil supply in the vehicle.
X DEF tank (BlueTEC vehicles): check the
level and top up if necessary (Y page 177).
X Tire-changing tool kit: check that the jack
is working and make sure you have the lug
wrench, a robust tow cable and a folding
spade in the vehicle.
X Wheels and tires: check the tire tread
depth and tire pressure.
X Check for damage and remove any foreign
objects, e.g. small stones, from the
wheels/tires.
X Replace any missing valve caps.
X Replace dented or damaged wheels.
X Rims: dented or bent rims can result in a
loss of tire pressure and damage the tire
bead. Therefore, check your rims before
driving off-road and replace them as
required. Checklist after driving off-road !
If you detect damage to the vehicle after
driving off-road, have the vehicle checked
immediately at a qualified specialist
workshop.
X Deactivate DSR (Y page 246).
X Vehicles with the AIRMATIC package:
lower the vehicle to a ride height suitable
for the road conditions, e.g. to the
highway/high-speed level.
X Cleant he headlamps and rear lights and
check for damage.
X Cleant he front and rear license plates.
X Cleant he wheels/tires with a water jet and
remove any foreign objects.
X Cleant he wheels, wheel housings and the
vehicle underside with a water jet; check
for any foreign objects and damage.
X Check whether twigs or other parts of
plants have become trapped. These
increase the risk of fire and can damage
fuel pipes, brake hoses or the rubber
bellows of the axle joints and propeller
shafts.
X After the trip, examine without fail the
entire undercarriage, wheels, tires, brakes,
bodywork structure, steering, chassis and
exhaust system for damage.
X After driving for extended periods across
sand, mud, gravel, water or in similarly dirty
conditions, have the brake discs, wheels,
brake pads/linings and axle joints checked
and cleaned.
X If you detect strong vibrations after off-road
travel, check for foreign objects in the
wheels and drive train and remove them if
necessary. Foreign objects can disturb the
balance and cause vibrations.
Driving over rough terrain places greater
demands on your vehicle than driving on
normal roads. After driving off-road, check
the vehicle. This allows you to detect damage
promptly and reduce the risk of an accident
to yourself and other road users. Driving tips
189Driving and parking Z

Driving on sand
Observe the following rules when driving on
sand:
R
vehicles wit hthe AIRMATIC package:
select a raised vehicle level.
R avoid high engine speeds.
R use the left-hand steering wheel paddle
shifter to shift to a lower gea rappropriate
to the terrain.
R drive quickly to overcome the rolling
resistance. Otherwise the vehicle's wheels
could become stuc kinloose ground.
R drive in the tracks of other vehicles if
possible. Make sure that:
-the tire ruts are not too deep.
- the sand is sufficiently firm.
- the ground clearance of the vehicle is
sufficient.
Tire ruts and gravel roads !
Check that the ruts are not too deep and
that your vehicle has sufficient clearance.
Otherwise, your vehicle could be damaged
or bottom out and get stuck.
Observe the following rules when driving
along ruts in off-road terrain or on roads with
loose gravel:
R vehicles with the AIRMATIC package:
select a raised vehicle level.
R avoid high engine speeds.
R shift to a lower gear using the left-hand
steering wheel paddle shifter.
R drive slowly.
R where ruts are too deep, drive with the
wheels of one side on the center grassy
area, if possible.
Driving over obstacles !
Obstacles could damage the floor of the
vehicle or components of the chassis. Ask
passengers for guidance when driving over
large obstacles. The passenger should
always keep a safe distance from the vehicle when doing so in order to avoid
injury as a result of unexpected vehicle
movements. After driving off-road or over
obstacles, check the vehicle for possible
damage, especially to the underbody and
the components of the chassis.
Observe the following rules when driving over
tree stumps, large stones and other
obstacles:
R raise the vehicle level.
R avoid high engine speeds.
R shift to a lower gear using the left-hand
steering wheel paddle shifter.
R drive very slowly.
R drive straight over the center of obstacles. Traveling uphill
Approach/departure angle G
WARNING
If you drive on a steep incline at an angle or
turn when driving on an incline, the vehicle
could slip sideways, tip and rollover. There is
a risk of an accident.
Always drive on a steep incline in the line of
fall (straight up or down) and do not turn the
vehicle.
R Observe the rules on off-road driving.
R Do not drive at an angle on slopes, inclines
or gradients, but instead follow the direct
line of fall. The maximum gradient-climbing
capability of your vehicle is 100%, which
corresponds to an approach/departure 190
Driving tipsDriving and parking

angle of 45°. Note that the climbing ability
of your vehicle depends on the terrain
conditions.
R When driving down an incline, make use of
the engine's braking effect. Observe the
engine speed; do no toverrev the engine.
R Drive slowly.
R Avoid high engine speeds. Drive at
appropriate engine speeds (maximum
3,000 rpm).
R Use the left-hand paddle shifter to shift into
a lower gearing ood time on long and steep
downhill gradients.
R Check the brakes after prolonged off-road
driving.
i Hill start assist will aid you when pulling
away on a hill.
For further information about hill start
assist, see (Y page 161).
Do not switch to transmission position N
when driving off-road. If you try to brake the
vehicle using the service brake, you could
lose control of the vehicle. If the gradient is
too steep for your vehicle, drive back down in
reverse gear.
Always observe the approach/departure
angle values (Y page 454).
Maximu mgradient-climbing capability Always observe the maximum gradient
climbing ability values (Y page 455).
Hilltops When driving up an uphill gradient, slightly
reduce pressure on the accelerator
immediately before reaching the brow of the
hill .Use the vehicle's own impetus to drive
over the top of the hill.
This style of driving prevents:
R the vehicle from lifting off the ground on the
brow of a hill
R the vehicle from traveling too quickly down
the other side Driving downhill R
Drive slowly.
R Do not drive at an angle down steep
inclines. Steer into the line of fall and drive
with the front wheels aligned straight.
Otherwise, the vehicle could slip sideways,
tip and rollover.
R Shift to a lower gear using the left-hand
paddle shifter before tackling steep
downhill gradients.
R Activate DSR. If this is not sufficient, brake
gently. When doing so, make sure that the
vehicle is facing in the direction of the line
of fall.
R Check that the brakes are working normally
after a long downhill stretch.
i The special off-road ABS setting enables
a precise, brief and repeated locking of the
front wheels. This causes them to dig into
loose earth. Be aware that the front wheels
easily skid across the ground surface if
completely braked and therefore lose their
ability to steer. Driving systems
Cruise control
General notes Cruise control maintains a constant road
speed for you. It brakes automatically in order
to avoid exceeding the set speed. You must
select a lower gear in good time on long and
steep downhill gradients, especially if the
vehicle is laden or towing a trailer. By doing
so, you will make use of the braking effect of
the engine. This relieves the load on the brake
system and prevents the brakes from
overheating and wearing too quickly.
Use cruise control only if road and traffic
conditions make it appropriate to maintain a
steady speed for a prolonged period. You can
store any road speed above 20 mph
(30 km/h). Driving systems
191Driving and parking Z

indicator 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 0002on the
corresponding side lights up red. This warning
is always emitted when a vehicle enters the
blind spot monitoring rang efrom behind or
from the side .When you overtake a vehicle,
the warning only occurs if the difference in
speed is less than 7mph (12 km/h).
The yellow indicator lamp goes out if reverse
gear is engaged. In this event, Blind Spot
Assist is no longer active.
The brightness of the indicator/warning
lamps is adjusted automatically according to
the ambient light.
Collision warning
If a vehicle is detected in the monitoring range
of Blind Spot Assist and you switch on the
corresponding turn signal, a double warning
tone sounds. Red warning lamp 0002flashes. If
the turn signal remains on, vehicles detected
are indicated by the flashing of red warning
lamp 0002.There are no further warning tones.
Switching on Blind Spot Assist X
Make sure that the radar sensor system
(Y page 276) and Blind Spot Assist (Y
page 273) are activated in the on-board
computer.
X Turn the SmartKey to position 2in the
ignition lock.
Warning lamps 0002in the exterior mirrors
light up red for approximately
1.5 seconds and then turn yellow.
Towing atrailer
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 Spo tAssist is deactivated. The indicator
lamp in the exterior mirrors lights up yellow,
and the Blind Spot Assist Currently Unavailable See Operator's Manual
message appears in the multifunction
display.
i
You can deactivate the indicator lamps in
the exterior mirrors.
To do so, switch off Blind Spot Assist when:
R the SmartKey is in position 2in the
ignition lock
R the engine is not running
R the electrical connection to the trailer
has been established
Lane Keeping Assist General notes
0002
Lane Keeping Assist camera
Lane Keeping Assist monitors the area in
front of your vehicle by means of a Driving systems
235Driving and parking Z

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 Make sure that the automatic transmission
is set to position P.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Vehicles with the AIRMATIC package:
select highway level.
X Vehicles with ADS: set ADS toAUTOor
COMF.
X Switch off the engine.
X Close all doors and the tailgate.
X Couple up the trailer.
X Establish all electrical connections.
X Check that the trailer lighting system is
working.
i Vehicles with the AIRMATIC package:
with a trailer attached, the vehicle will
always remain at highway level. When
coupling up a trailer, please observe the
following:
R Unless highway level has been set
manually, the vehicle is automatically
lowered to highway level. This is the case
if a speed of 5mph(8km/h) is reached.
R High-speed level is not available.
These restrictions apply to all accessories
powered through a connectio nto the trailer
power socket of your vehicle, e.g. a bicycle
carrier.
Observe the maximum permissible trailer
dimensions (width and length).
Most U.S. states and all Canadia nprovinces
require by law:
R Safety chains between the towing vehicle
and the trailer. The chains should be cross-
wound under the trailer drawbar. They must
be fastened 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 As eparate brake system for certain types
of trailer.
R As afety switch for braked trailers. Check
the specific legal requirements applicable
to your state.
If the trailer detaches from the towing
vehicle, the safety switch applies the
trailer's brakes. Towing
atrailer
There are numerous legal requirements
concerning the towing of a trailer, e.g .speed
restrictions. Make sure that your vehicle/
trailer combination complies with the local
requirements not only in your area of
residence but also at any location to which
you are traveling. The police and local
authorities can provide reliable information.
Please observe the following when towing a
trailer:
R In order to accumulate driving experience
and accustom yourself to the new handling
characteristics, practice the following at a
location where there is no traffic:
-Cornering
- Stopping
- Backing up
R Before driving, check:
-the trailer tow hitch
- the safety switch for braked trailers
- the safety chains
- electrical connections
- the lights
- the 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. Towing
atrailer
257Driving an d parking Z

R
Secure any objects on the traile rto prevent
the cargo from slipping when the vehicle is
in motion.
R If you couple up a trailer, regularly check
that the cargo is securely fastened and
make sure that the trailer lamps and (if
applicable) the trailer brakes are
functioning correctly.
R Bear in mind that the handling will be less
stable when towing a trailer than when
driving without one. Avoid sudden steering
movements.
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, avoid abrupt braking. Depress
the brake pedal moderately at first, so that
the trailer can activate its own brakes. Then
increase the pressure on the brake pedal.
R If the automatic transmission repeatedly
shifts between gears on uphill or downhill
gradients, shift to a lower gear using the
left-hand steering wheel paddle shifter.
Al ower 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
installed, the trailer brakes.
R If the coolant temperature increases
dramatically while the air-conditioning
system is switched on, switch off the air-
conditioning system.
Coolant heat can additionally be dissipated
by opening the windows and by setting the
blower fan and the interior temperature to
maximum.
R When overtaking, pay particular attention
to the extended length of your vehicle/
trailer combination. Due to the length of your vehicle/trailer
combination, you will have to travel an
additional distance beyond the vehicle you
are overtaking before returning to the
previous lane. Decoupling
atrailer 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 overru nbrake
is engaged. G
WARNING
Vehicles with level control:
The vehicle is lowered as soon as you
disconnect the trailer cable. This could result
in yourl imbs or those of other people that are
betwee nthe vehicle body and tires or
underneath 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 disconnectt he 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 Make sure that the automatic transmission
is set to position P.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Close all doors and the tailgate.
X Apply the trailer's parking brake.
X Detach the trailer cable and decouple the
trailer.
X Switch off the engine. 258
Towing
atrailerDriving an d parking

Display messages Possible causes/consequences and
0001 Solutions
0004
Auto
Lamp Function
Inoperative The ligh
tsensor is defective.
X Visit a qualified specialist workshop. 0004
Switch Off Lights The lights are still switched on when you leave the vehicle. A
warning tone also sounds.
X
Turn the light switch to 0006.Adaptive Highbeam
Assist Inoperative Adaptive Highbeam Assist is faulty.
X
Visit a qualified specialist workshop. Adaptive Highbeam
Assist Currently
Unavailable See
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 again,
the Adaptive Highbeam Assist Now Available message is
displayed.
Adaptive Highbeam Assist is operational again. Engine
Display messages Possible causes/consequences and
0001 Solutions
000F
Check Coolant
Level See
Operator's Manual 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.
X Add coolant, observing the warning notes before doing so
(Y page 367).
X If coolant needs to be added more often than usual, have the
engine coolant system checked at a qualified specialist
workshop. 000E The fan moto
ris faulty.
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. 298
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
0001 Solutions
000E
Coolant Too Hot
Stop Vehicle Turn
Engine Off The coolan
tis too hot.
Aw arning tone also sounds.
G WARNING
Do no tdrive when youre ngine is overheated. Thi scan cause some
fluids which may have leaked into the engine compartmen tto
catch fire.
Stea mfrom the overheated engine can also cause serious burns
which can occur just by opening the hood.
There is a risk of injury.
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 179).
X Waitu ntil the engine has cooled down.
X Make sure tha tthe 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 display message goes out
and the coolant temperature is below 248 ‡ (120 †).
Otherwise, the engine could be damaged.
X Pay attention to the coolant temperature display.
X If the temperature increases again, visit a qualified specialist
workshop immediately.
Under normal operating conditions and with the specified coolant
level, the coolant temperature may rise to 248 ‡ (120 †). 000B The battery is not being charged.
Aw
arning tone also sounds.
Possible causes are:
R a defective alternator
R a torn poly-V-belt
R a malfunction in the electronics
X Pull ove rand stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Ope nthe hood.
X Check whether the poly-V-belt is torn.
If the poly-V-belt is torn:
! Do not continue driving. The engine could otherwise overheat.
X Consult a qualified specialist workshop.
If the poly-V-belt is not damaged:
X Visit a qualified specialist workshop. Display messages
299On-board computer and displays Z

Display messages Possible causes/consequences and
0001 Solutions
0013
Check Engine Oil
At Next Refueling The engine oil level has dropped to the minimum level.
Aw
arning tone also sounds.
X Chec kthe oil level when next refueling, at the latest
(Y page 365).
X If necessary, add engine oil (Y page 366).
X Have the engine checked at a qualified specialist workshop if
engine oil needs to be added more often than usual.
! Avoid long journeys with too little engine oil. The engine will
otherwise be damaged.
Information on approved engine oils can be obtained from any
qualified specialist workshop or on the Internet at http://
bevo.mercedes-benz.com. 0013
Check Engine Oil
Level (Add 1 quart) AMG vehicles: the engine oil level is too low.
X
Check the oil level when next refueling, at the latest
(Y page 365).
X If necessary, add engine oil (Y page 366).
X Have the engine checked at a qualified specialist workshop if
engine oil needs to be added more often than usual.
! Avoid long journeys with too little engine oil. The engine will
otherwise be damaged.
Information on approved engine oils can be obtained from any
qualified specialist workshop or on the Internet at http://
bevo.mercedes-benz.com. 0012
Fuel Level Low The fuel level has dropped into the reserve range.
X
Refuel at the nearest gas station. 000A There is only a very small amount of fuel in the fuel tank.
X
Refuel at the nearest gas station without fail. 0012
Gas Cap Loose 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.
If the fuel filler cap is not correctly closed:
X Close the fuel filler cap.
If the fuel filler cap is correctly closed:
X Visit a qualified specialist workshop. 300
Display messagesOn-board computer and displays

Display messages Possible causes/consequences and
0001 Solutions
0012
Ultra Low-sulfur
Diesel Fuel Only Vehicles with a diesel engine: the fuel level has fallen below the
reserve range.
X Refuel at the neares tgas station.
X Only use commercially available vehicular ULTRA-LOW SULFUR
HIGHWAY DIESEL FUEL (ULSD ,15ppm SULFUR MAXIMUM). 0003
Replace Air Filter Vehicles with a diesel engine
:the engine air filter is dirty and must
be replaced.
X Visit a qualified specialist workshop. 0002
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. 0002
Check
Additive See
Operator's Manual The DEF tank is almost empty.
X
Have the DEF tank filled as soon as possible at aqualified
specialist workshop (Y page 177).0002
Remaining Starts:
16 The DE
Flevel has fallen to a minimum. You can start the engine a
further 16 times.
X Have the DEFt ank filled immediately at a qualified specialist
workshop (Y page 177).
i You can start the engine a further 16 times. If DE Fis 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 177).Driving systems
Display messages Possible causes/consequences and
0001 Solutions
0002
Attention Assist:
Take a Break! Based on certain criteria, ATTENTION ASSIST has detected fatigue
or
alack of concentration on th epart of th edriver. 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. 0002
Attention Assist
Inoperative ATTENTION ASSIST is inoperative.
X Visi taqualified specialist workshop. Display messages
301On-board computer and displays Z