2012 MERCEDES-BENZ A CLASS Owners Manual

Display messages Possible causes/consequences and
M Solutions6
Rear centre mal‐
function Consult
workshop SRS has malfunctioned at the rear centre. The
6 warning lamp
also lights up in the instrument cluster.
G WARNING
The airbags or belt tensioners may either be triggered uninten-
tionally or, in the event of an accident, may not be triggered.
This poses an increased risk of injury.
X Visit a qualified specialist workshop. 6
Left

windowbag mal‐
function Consult
workshop or Right
windowbag malfunc‐
tion Consult work‐
shop There is a malfunction in the left-hand and/or right-hand window-
bag.
The 6 warning lamp also lights up in the instrument clus-
ter.
G WARNING
The left or right windowbag may either be triggered unintentionally
or, in the event of an accident, may not be triggered.
This poses an increased risk of injury.
X Visit a qualified specialist workshop. Lights
i Display messages about LEDs:
This display message will only appear if all the LEDs have failed. Display messages Possible causes/consequences and
M Solutionsb
Left cornering
light or Right cor‐
nering light The left or right-hand cornering light is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Left dipped beam 
or Right dipped
beam The left or right-hand dipped-beam headlamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Trailer left tail
lamporTrailer
right tail lamp The left or right-hand trailer tail lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself.
or
X Visit a qualified specialist workshop. Display messages
239
On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutionsb
Trailer left indi‐
cator or Trailer
right indicator The left or right-hand trailer turn signal lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself.
or
X Visit a qualified specialist workshop. b
Trailer brake lamp The trailer brake lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself.
or
X Visit a qualified specialist workshop. b
Rear left indica‐
tor or Rear right
indicator The rear left-hand or rear right-hand turn signal is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Front left indica‐
tor or Front right
indicator The front left-hand or front right-hand turn signal is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Left
mirror indica‐
tor or Right mir‐
ror indicator The turn signal in the left-hand or right-hand exterior mirror is
faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Third brake lamp The third brake lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Left brake lamp
 or 
Right brake lamp The left or right-hand brake lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop.240
Display messages
On-board computer and displays

Display messages Possible causes/consequences and
M Solutionsb
Left-hand tail
lamp/brake lamp
 or 
Right-hand tail
lamp/brake lamp The left or right-hand tail lamp/brake lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Left main beam or 
Right main beam The left or right-hand main-beam headlamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Number plate lamp The left or right-hand licence plate lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Front
foglamp left  
or Front foglamp
right The left-hand or right-hand front foglamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Rear fog lamp The rear foglamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Front

left parking
lamp or Front
right parking lamp The front left or front right parking lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Reversing light The reversing lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. Display messages
241
On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutionsb
Left tail lamp or 
Right tail lamp The left or right-hand tail lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Left daytime driv‐
ing lamp or Right
daytime driving
lamp The left-hand or right-hand daytime driving lamp is faulty.
X
Check whether you are permitted to replace the bulb yourself
(Y page 112).
or
X Visit a qualified specialist workshop. b
Intell. Light Sys‐
tem inoperative The Intelligent Light System is faulty. The lights remain available
without the Intelligent Light System.
X
Visit a qualified specialist workshop. b
Malfunction See
Owner's Manual The exterior lighting is faulty.
X
Visit a qualified specialist workshop. Vehicles with trailer tow hitch: a fuse may have blown.
X
Check the fuses (Y page 314).
X If necessary, replace the blown fuse. Observe the warning notes
as you do so.
If the display message continues to be displayed:
X Visit a qualified specialist workshop. b
AUTO
lights inoper‐
ative The light sensor is faulty.
X
Visit a qualified specialist workshop. b
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.242
Display messages
On-board computer and displays

Display messages Possible causes/consequences and
M SolutionsAdaptive Main-beam
Assist inoperative Adaptive Highbeam Assist is faulty.
X
Visit a qualified specialist workshop. Adaptive Main-beam
Assist currently
unavailable See
Owner's Manual Adaptive Highbeam Assist is deactivated and temporarily inoper-
ative. Possible causes:
R
the windscreen is dirty in the camera's field of vision.
R visibility is impaired due to heavy rain, snow or fog.
X Clean the windscreen.
If the system detects that the camera is fully operational again,
the Adaptive Main-beam Assist available again message
is displayed.
Adaptive Highbeam Assist is operational again. Engine
Display messages Possible causes/consequences and
M Solutions+
Top
up coolant See
Owner'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 Top up the coolant, observing the warning notes before doing
so (Y page 288).
X If the coolant needs topping up more often than usual, have the
engine coolant system checked at a qualified specialist work-
shop. ? The fan motor is faulty.
X
If the coolant temperature is below 120 †, you can continue
driving to the nearest qualified specialist workshop.
X Avoid heavy loads on the engine as you do so, e.g. driving in
mountainous terrain and stop-start traffic. Display messages
243
On-board computer and displays Z

Display messages Possible causes/consequences and
M Solutions?
Coolant Stop vehi‐
cle Switch engine
off The coolant is too hot.
A warning tone also sounds.
G WARNING
Never drive with an overheated engine. Driving when your engine
is overheated can cause some fluids which may have leaked into
the engine compartment to catch fire.
Steam
from an overheated engine can cause serious burns, which
can occur just by opening the bonnet.
There is a risk of injury.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle against rolling away ( Y page 162).
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 frozen slush.
X Do not start the engine again until the display message goes out
and the coolant temperature is below

120 †. The engine may
otherwise 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
120 †.# The battery is not being charged.
A warning tone also sounds.
Possible causes:
R
faulty alternator
R torn poly-V-belt
R a malfunction in the electronics
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Open the bonnet.
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 OK:
X Visit a qualified specialist workshop immediately.244
Display messages
On-board computer and displays

Display messages Possible causes/consequences and
M Solutions4
Check eng. oil
lev. when next
refuelling The engine oil level has dropped to the minimum level.
A warning tone also sounds.
X
Check the oil level when next refuelling, at the latest
(Y page 286).
X If necessary, top up the engine oil (Y page 287).
X Have the engine checked at a qualified specialist workshop if
the engine oil needs topping up more often than usual. æ
Reserve fuel level The fuel level has dropped into the reserve range.
The auxiliary heating cannot be operated.
X
Refuel at the nearest filling station. ç There is very little fuel in the fuel tank.
The auxiliary heating cannot be operated.
X
Refuel at the nearest filling station without fail. ¸
Replace
air cleaner Vehicles with a diesel engine: the engine air filter is dirty and must
be replaced.
X
Visit a qualified specialist workshop.
i This message does not appear for the 180 CDI BlueEFFI-
CIENCY, manual transmission model A. !
Clean

the fuel fil‐
ter Vehicles with a diesel engine: there is water in the fuel filter. The
water must be drained off.
X
Visit a qualified specialist workshop. Driving systems
Display messages Possible causes/consequences and
M SolutionsÀ
Attention Assist:
Drowsiness detec‐
ted 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 that you
get enough rest. À
Attention Assist
inoperative ATTENTION ASSIST is inoperative.
X
Visit a qualified specialist workshop. Display messages
245
On-board computer and displays Z

Display messages Possible causes/consequences and
M SolutionsSpeed Limit Assist
Currently unavail‐
able See Owner's
Manual Speed Limit Assist is deactivated and temporarily inoperative.
Possible causes:
R
the windscreen is dirty in the camera's field of vision.
R visibility is impaired due to heavy rain, snow or fog.
X Clean the windscreen.
If the system detects that the camera is fully operational, the dis-
play message disappears.
Speed Limit Assist is operational again. Speed Limit Assist:
Unavailable in
this country Speed Limit Assist is only available in certain countries.
X
Drive on.
Speed
Limit Assist is available again as soon as you drive into a
country in which its use is approved. Speed Limit Assist
inoperative Speed Limit Assist is faulty.
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 179). 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 179). Radar sensor deac‐
tivated See Own‐
er's Manual The radar sensor system is deactivated.
X
Check whether or not the radar sensor system may be activated
(Y page 350).
X Switch on the radar sensor system (Y page 223). Radar sensor deac‐
tivated

autom. See
Owner's Manual Vehicles with a navigation system: the vehicle is close to a radio
telescope
facility and is therefore prohibited from transmitting any
radar signals. The radar sensor system is deactivated automati-
cally.
If Blind Spot Assist was activated, it is no longer available. The
yellow 9 indicator lamps also light up in the exterior mirrors.
X Drive on.
Blind

Spot Assist is available again as soon as the vehicle is far
enough away from the radio telescope facility ( Y page 350).246
Display messages
On-board computer and displays