warning lights MERCEDES-BENZ S-CLASS SEDAN 2012 Service Manual

Display messagesPossible causes/consequences and M Solutions$ (USA only)
J (Canada only)
Service See Oper.
ManualThere is a malfunction in the system. The brake system continues
to operate normally.XDrive on carefully.XVisit a qualified specialist workshop.$ (USA only)
J (Canada only)
Check Brake Fluid
LevelGRisk of accident
There is not enough brake fluid in the brake fluid reservoir.
Additionally, the red $ (USA only)/ J (Canada only)
warning lamp lights up in the instrument cluster and a warning
tone sounds.
XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.XApply the electric parking brake.XConsult a qualified specialist workshop.XDo not add brake fluid. This will not rectify the malfunction.GWARNING
Driving with the message Check Brake Fluid Level displayed can result in an accident. Have
your brake system checked immediately.
Do not add brake fluid before checking the brake system. Overfilling the brake fluid reservoir can
result in spilling brake fluid on hot engine parts and the brake fluid catching fire. You can be
seriously burned.
Display messagesPossible causes/consequences and M SolutionsG
Tele Aid
InoperativeUSA only: one or more of the main functions in the mbrace system
are malfunctioning.
Canada only: one or more of the main functions of the TELEAID
system are malfunctioning.XUSA only: have the mbrace system checked at a qualified
specialist workshop.XCanada only: have the TELEAID system checked at a qualified
specialist workshop.PRE-SAFE
Inoperative See
Oper. ManualGRisk of injury
Important functions of PRE-SAFE ®
have failed. All other occupant
safety systems, e.g. air bags, remain available.
XVisit a qualified specialist workshop immediately.398Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M SolutionsPRE-SAFE
Functions
Currently Limited
See Operator's
ManualGRisk of accident
PRE-SAFE ®
Brake is temporarily inoperative. Possible causes are:
R the DISTRONIC PLUS cover in the radiator grill is dirty.
R function is impaired due to heavy rain or snow.
R the sensors in the bumpers 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.
If the display message does not disappear:
XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.XApply the electric parking brake.XClean the DISTRONIC PLUS cover in the radiator grill
( Y page 470).XClean the bumpers ( Y page 470).XRestart the engine.
If the system detects that the sensors are fully operational, the
display message disappears.
PRE-SAFE ®
Brake is operational again.
PRE-SAFE
Function Limited
See Oper. ManualGRisk of accident
PRE-SAFE ®
Brake is defective. BAS PLUS or the distance warning
signal may also have failed.
XVisit a qualified specialist workshop.6
SRS Malfunction
Service RequiredGRisk of injury
There is a malfunction in the SRS (Supplemental Restraint
System). The 6 warning lamp also lights up in the instrument
cluster.
XVisit a qualified specialist workshop.6
Front Left SRS
Malfunction
Service Required  
or  Front Right SRS
Malfunction
Service RequiredGRisk of injury
SRS has malfunctioned at the front on the left or right. The 6
warning lamp also lights up in the instrument cluster.
XVisit a qualified specialist workshop.Display messages399On-board computer and displaysZ

Display messagesPossible causes/consequences and M Solutions6
Rear Left SRS
Malfunction
Service Required  
or  Rear Right SRS
Malfunction
Service RequiredGRisk of injury
SRS has malfunctioned at the rear on the left or right. The 6
warning lamp also lights up in the instrument cluster.
XVisit a qualified specialist workshop.6
Rear Center SRS
Malfunction
Service RequiredGRisk of injury
SRS has malfunctioned at the rear center. The 6 warning lamp
also lights up in the instrument cluster.
XVisit a qualified specialist workshop.6
Left Side Curtain
Airbag Malfunction
Service Required  
or  Right Side
Curtain Airbag
Malfunction
Service RequiredGRisk of injury
There is a malfunction in the left-hand or right-hand window
curtain air bag.
The 6 warning lamp also lights up in the instrument cluster.
XVisit a qualified specialist workshop.GWARNING
In the event a malfunction of the SRS is indicated as outlined above, the SRS may not be
operational.
For your safety, we strongly recommend that you contact an authorized Mercedes-Benz Center
immediately to have the system checked. Otherwise the SRS may not be activated when needed
in an accident, which could result in serious or fatal injury, or it might deploy unexpectedly and
unnecessarily which could also result in injury.
400Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M Solutionsb
Please Switch Off
LightsThe lights are still switched on when you leave the vehicle. A
warning tone also sounds.XTurn the light switch to $ or c .
or
XIf the rear fog lamp is switched on: press the light switch in to
the stop.Adaptive High-beam
Assist InoperativeAdaptive Highbeam Assist is faulty.XVisit a qualified specialist workshop.
Engine
Display messagesPossible causes/consequences and M Solutions+
Check Coolant
Level See Oper.
ManualThe coolant level is too low.XAdd coolant, observing the warning notes when doing so
( Y page 463).XIf coolant needs to be added more often than usual, have the
engine coolant system checked at a qualified specialist
workshop.GWARNING
Do not spill antifreeze on hot engine parts. Antifreeze contains ethylene glycol which may burn
if it comes into contact with hot engine parts. You could be seriously burned.
! The coolant level is too low. Avoid making long journeys with too little coolant in the cooling
system. The engine will otherwise be damaged.
The display messages and the corresponding symbol that indicate that the coolant level is
too low must not be ignored.
Display messagesPossible causes/consequences and M Solutions?
Coolant Low Stop
Vehicle Turn
Engine OffThe coolant is too hot.XPull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.XMake sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.XWait until the display message disappears before restarting the
engine. Otherwise, the engine could be damaged.XPay attention to the coolant temperature display.XIf the temperature increases again, visit a qualified specialist
workshop immediately.406Display messagesOn-board computer and displays

Driving systemsDisplay messagesPossible causes/consequences and M SolutionsÀ
Attention Assist:
Drowsiness
DetectedBased on specific criteria, ATTENTION ASSIST 20
has determined
that the driver is tired or paying less attention. A warning tone also
sounds.XIf necessary, take a break.
During long journeys, take regular breaks in good time so you get
enough rest.
À
Attention Assist
InoperativeATTENTION ASSIST 20
has failed.XVisit a qualified specialist workshop.Á
Night View Assist
InoperativeNight View Assist Plus is defective.XVisit a qualified specialist workshop.Á
Night View Assist
Currently
UnavailableThe temperature of the camera is too high.XWait until you see the Night View Assist Available
Again display message.
You can also:
XFold the camera cover down ( Y page 471).XAdjust the air distribution of the automatic air conditioning
upwards.Á
Night View Assist
Lights Must Be Set
to AUTO or ONA condition for activating Night View Assist Plus has not been
fulfilled.XTurn the light switch to c or L .Á
Night View Assist
Not In Reverse GearA condition for activating Night View Assist Plus has not been
fulfilled.XShift the transmission to P, N or D.Á
Night View Assist
Lights ON or AUTO,
Not in R GearA condition for activating Night View Assist Plus has not been
fulfilled.XTurn the light switch to c or L .XShift the transmission to P, N or D.20
Not available on hybrid vehicles.410Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M SolutionsÂ
Key Not
Detected (White
display message)The KEYLESS-GO key cannot be detected at present.XChange the location of the key with the KEYLESS-GO functions
in the vehicle.
If the KEYLESS-GO key is still not detected:
XOperate the vehicle with the SmartKey in the ignition lock.Â
Key Detected In
VehicleThe KEYLESS-GO key has been detected inside the vehicle during
locking.XRemove the KEYLESS-GO key from the vehicle.Â
Remove 'Start'
Button and Insert
KeyKEYLESS-GO is temporarily malfunctioning or is defective.XInsert the SmartKey into the ignition lock and turn it to the
desired position.XVisit a qualified specialist workshop.Â
Close Doors to
Lock VehicleAt least one door is open. A warning tone also sounds.XClose all doors and lock the vehicle again.
Warning and indicator lamps in the instrument cluster
Seat belts
ProblemPossible causes/consequences and M Solutions7
After starting the
engine, the red seat
belt warning lamp lights
up for six seconds.The seat belt warning lamp reminds the driver and front passenger
to fasten their seat belts.XFasten your seat belt ( Y page 61).7
After starting the
engine, the red seat
belt warning lamp lights
up. In addition, a
warning tone sounds
for up to six seconds.GRisk of injury
The driver's seat belt is not fastened.
XFasten your seat belt ( Y page 61).
The warning tone ceases.422Warning and indicator lamps in the instrument clusterOn-board computer and displays

ProblemPossible causes/consequences and M Solutions7
The red seat belt
warning lamp lights up
after the engine starts,
as soon as the driver's
or the front-passenger
door is closed.GRisk of injury
The driver or front passenger has not fastened their seat belt.
XFasten your seat belt ( Y page 61).
The warning lamp goes out.GRisk of injury
There are objects on the front-passenger seat.
XRemove the objects from the front-passenger seat and stow
them in a secure place.
The warning lamp goes out.7
The red seat belt
warning lamp flashes
and an intermittent
audible warning
sounds.GRisk of injury
The driver or front passenger has not fastened their seat belt. In
addition, you are driving faster than 15 mph (25 km/h) or you have
briefly driven faster than 15 mph (25 km/h).
XFasten your seat belt ( Y page 61).
The warning lamp goes out and the intermittent warning tone
ceases.GRisk of injury
There are objects on the front-passenger seat. In addition, you are
driving faster than 15 mph (25 km/h) or you have briefly driven
faster than 15 mph (25 km/h).
XRemove the objects from the front-passenger seat and stow
them in a secure place.
The warning lamp goes out and the intermittent warning tone
ceases.Warning and indicator lamps in the instrument cluster423On-board computer and displaysZ

ProblemPossible causes/consequences and M Solutions֌
The yellow ESP ®
and
ESP ®
OFF warning
lamps are lit while the
engine is running.GRisk of accident
ESP ®
, BAS, PRE-SAFE ®
, the HOLD function and hill start assist are
temporarily unavailable.
BAS PLUS and PRE-SAFE ®
Brake may also have failed.
ESP ®
will not stabilize the vehicle if it starts to skid or if a wheel
starts to spin.
Self-diagnosis is not yet complete.
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
ATTENTION ASSIST 21
is deactivated.
XCarefully drive a short distance on a suitable stretch of road,
making slight steering movements at a speed above 12 mph
(20 km/h).
The functions mentioned above are available again when the
warning lamp goes out.
If the warning lamp is still on:
XObserve the additional display messages in the multifunction
display.XDrive on carefully.XVisit a qualified specialist workshop.F (USA only)
! (Canada only)
The red indicator lamp
for the electric parking
brake flashes and/or
the yellow warning
lamp for the electric
parking brake lights up.The electric parking brake is temporarily malfunctioning or
defective.XObserve the additional display messages in the multifunction
display.6
The red SRS warning
lamp is lit while the
engine is running.GRisk of injury
The restraint systems are malfunctioning. The air bags or ETDs
may either be triggered unintentionally or, in the event of an
accident, not be triggered at all.
XDrive on carefully.XVisit a qualified specialist workshop immediately.21 Not available on hybrid vehicles.428Warning and indicator lamps in the instrument clusterOn-board computer and displays

GWARNING
In the event a malfunction of the SRS is indicated as outlined above, the SRS may not be
operational.
For your safety, we strongly recommend that you contact an authorized Mercedes-Benz Center
immediately to have the system checked. Otherwise the SRS may not be activated when needed
in an accident, which could result in serious or fatal injury, or it might deploy unexpectedly and
unnecessarily which could also result in injury.
Engine
ProblemPossible causes/consequences and M Solutions;
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 a gasoline engine)
R in the fuel system
The emission limit values may be exceeded and the engine may
be running in emergency mode.XHave 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 324).XStart 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.Warning and indicator lamps in the instrument cluster429On-board computer and displaysZ

ProblemPossible causes/consequences and M SolutionsThe 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.XObserve the additional display messages in the multifunction
display.XCheck that the fuel filler cap is correctly closed.XIf the fuel filler cap is not correctly closed: close the fuel filler
cap.XIf the fuel filler cap is closed: visit a qualified specialist
workshop.The yellow reserve fuel
warning lamp lights up
while the engine is
running.The fuel level has dropped into the reserve range.XRefuel at the nearest gas station.
Driving systems
ProblemPossible causes/consequences and M Solutions·
The red distance
warning lamp lights up
while the vehicle is in
motion. A warning tone
also sounds.GRisk of accident
You are approaching a vehicle or a stationary obstacle in your line
of travel at too high a speed.
XBe prepared to brake immediately.XPay careful attention to the traffic situation. You may have to
brake or take evasive action.
More information about DISTRONIC PLUS ( Y page 336) and
PRE-SAFE ®
Brake ( Y page 77).
430Warning and indicator lamps in the instrument clusterOn-board computer and displays