MERCEDES-BENZ B-CLASS 2012 Owners Manual

This display message will only appear if all LEDs have failed.
Display messages Possible causes/consequences and
M Solutionsb
Check Left
Cornering Light
 or 
Check Right
Cornering Light The left or right-hand cornering light is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Left Low
Beam or Check
Right Low Beam The left or right-hand low-beam headlamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Rear Left
Turn Signal or 
Check Rear Right
Turn Signal The rear left-hand or rear right-hand turn signal is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Front Left
Turn Signal or 
Check Front Right
Turn Signal The front left-hand or front right-hand turn signal is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Left Mirror
Turn Signal or 
Check
Right
Mirror
Turn Signal The turn signal in the left-hand or right-hand exterior mirror is
defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Center
Brake
Lamp The high-mounted brake lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. Display messages
209On-board computer and displays Z
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Display messages Possible causes/consequences and
M Solutionsb
Check Left Brake
Lamp or Check
Right Brake Lamp The left or right-hand brake lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Left Tail
and Brake Lamps
 or 
Check Right Tail
and Brake Lamps The left or right-hand tail lamp/brake lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Left High
Beam or Check
Right High Beam The left or right-hand high beam is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
License Plate Lamp The left or right-hand license plate lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Left Fog
Lamp or Check
Right Fog Lamp The left-hand or right-hand front fog lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Rear Fog Lamp The rear fog lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Front Left
Parking Lamp or 
Check Front Right
Parking Lamp The front left or front right parking or standing lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop.210
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Display messages Possible causes/consequences and
M Solutionsb
Backup Light The backup lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Left Tail
Lamp or Check
Right Tail Lamp The left or right-hand tail lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Front Left
Sidemarker Lamp
 or 
Check Front Right
Sidemarker Lamp The left or right front side marker lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Rear Left
Sidemarker Lamp
 or 
Check Rear Right
Sidemarker Lamp The rear left or right side marker lamp is defective.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Check Left
Daytime
Running Light
 or 
Check Right
Daytime Running
Light The left-hand or right-hand daytime running lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 104).
or
X Visit a qualified specialist workshop. b
Active Light
System Inoperative The active light function is defective.
X
Visit a qualified specialist workshop. b
Malfunction See
Operator's Manual The exterior lighting is defective.
X
Visit a qualified specialist workshop. b
Auto Lamp Function
Inoperative The light sensor is defective.
X
Visit a qualified specialist workshop. Display messages
211
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Display messages Possible causes/consequences and
M Solutionsb
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 Ã. 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
M Solutions+
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 269).
X If coolant needs to be added more often than usual, have the
engine coolant system checked at a qualified specialist
workshop. ? The fan motor is 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.212
Display messages
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Display messages Possible causes/consequences and
M Solutions?
Coolant Too Hot
Stop Vehicle Turn
Engine Off The coolant is too hot.
A warning tone also sounds.
G WARNING
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.
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 149).
X Wait until the engine has cooled down.
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 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 †). # The battery is not being charged.
A warning tone also sounds.
Possible causes are:
R
a defective alternator
R a torn poly-V-belt
R a malfunction in the electronics
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.
X Open the 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 immediately. Display messages
213
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Display messages Possible causes/consequences and
M Solutions4
Check Engine Oil
At Next Refueling The engine oil level has dropped to the minimum level.
A warning tone also sounds.
X
Check the oil level when next refueling, at the latest
(Y page 267).
X If necessary, add engine oil ( Y page 268).
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 (USA only). æ
Fuel Level Low The fuel level has dropped into the reserve range.
X
Refuel at the nearest gas station. ç There is only a very small amount of fuel in the fuel tank.
X
Refuel at the nearest gas station without fail. æ
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.214
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Driving systems
Display messages Possible causes/consequences and
M SolutionsÀ
Attention Assist:
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
Inoperative ATTENTION ASSIST is inoperative.
X
Visit a qualified specialist workshop. ë
Off The HOLD function is deactivated. The vehicle is skidding.
A warning tone also sounds.
X
Reactivate the HOLD function later (Y page 167). The HOLD function is deactivated. When the brake pedal is firmly
depressed, an activation condition is not fulfilled.
A warning tone also sounds.
X
Check the activation conditions for the HOLD function
(Y page 167). Radar Sensor
Deactivated See
Operator's Manual The radar sensor system is deactivated.
X
Switch on the radar sensor system (Y page 199). Lane Keeping
Assist Currently
Unavailable See
Operator's Manual Lane Keeping 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.
R there are no lane markings for a longer period.
R the lane markings

are worn, dark or covered, e.g. by dirt or snow.
When the causes stated above no longer apply, the display
message disappears.
Lane Keeping Assist 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 ( Y page 149).
X Clean the windshield. Display messages
215
On-board computer and displays Z
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Display messages Possible causes/consequences and
M SolutionsLane Keeping
Assist Inoperative Lane Keeping Assist is faulty.
X
Visit a qualified specialist workshop. Blind Spot Assist
Currently
Unavailable See
Operator's
ManualBlind Spot
Assist Currently
Unavailable See
Operator's Manual Blind Spot Assist is temporarily inoperative. Possible causes are:
R
the sensors are dirty.
R function is impaired due to heavy rain or snow.
R the radar sensor system is outside the operating temperature
range.
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.
The yellow 9 indicator lamps also light up in the exterior
mirrors.
When the causes stated above no longer apply, the display
message disappears.
Blind Spot Assist 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 ( Y page 149).
X Clean the sensors ( Y page 275).
X Restart the engine. Blind Spot Assist
Inoperative Blind Spot Assist is defective.
The yellow
9 indicator lamps also light up in the exterior
mirrors.
X Visit a qualified specialist workshop. Park Assist
Canceled The driver's door is open and the driver's seat belt has not been
fastened.
X
Repeat the parking process with the seat belt fastened and the
driver's door closed. You have inadvertently touched the multifunction steering wheel
while steering intervention was active.
X
While steering intervention is active, make sure that the
multifunction steering wheel is not touched unintentionally. The vehicle has started to skid and ESP
®
has intervened.
X Use Active Parking Assist again later (Y page 172).216
Display messagesOn-board computer and displays
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Display messages Possible causes/consequences and
M SolutionsPark Assist
Inoperative You have just carried out a large number of turning or parking
maneuvers.
Active Parking Assist will become available again after
approximately ten minutes (
Y page 172).
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Switch off and restart the engine.
If the display message continues to be displayed:
X Visit a qualified specialist workshop. PARKTRONIC is defective.
X
Visit a qualified specialist workshop. DISTRONIC PLUS Off DISTRONIC PLUS has been deactivated (
Y page 159). If it was
deactivated automatically, a warning tone also sounds. DISTRONIC PLUS Now
Available DISTRONIC PLUS is operational again after having been
temporarily
unavailable. You
can now reactivate DISTRONIC PLUS
(Y page 159). DISTRONIC PLUS
Currently
Unavailable See
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 trim 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 ( Y page 149).
X Clean the sensors in the radiator trim (Y page 275).
X Restart the engine. Display messages
217
On-board computer and displays Z
ProCarManuals.com

Display messages Possible causes/consequences and
M SolutionsDISTRONIC PLUS
Inoperative DISTRONIC PLUS is defective. Adaptive Brake Assist may also
have failed.
A warning tone also sounds.
X
Visit a qualified specialist workshop. DISTRONIC PLUS
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
--- mph An activation condition for DISTRONIC PLUS is not fulfilled.
X
Check the activation conditions for DISTRONIC PLUS
(Y page 161). Cruise Control
Inoperative Cruise control is defective.
A warning tone also sounds.
X
Visit a qualified specialist workshop. Cruise Control
--- mph A condition for activating cruise control has not been fulfilled.
You have tried to store a speed below
20 mph (30 km/h), for
example.
X If conditions permit, drive faster than
20 mph (30 km/h) and
store the speed.
X Check the activation conditions for cruise control
(Y page 158).218
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