2014 MERCEDES-BENZ C-CLASS SALOON ECU

Display messages
Possible causes/consequences and
M
MSolutions The red
!indicator lamp flashes and the yellow !warning
lamp is lit.
The electric parking brake is malfunctioning.
To release:
X Switch off the ignition and turn it back on.
X Release the electric parking brake manually.
To apply:
X Switch off the ignition and turn it back on.
X Apply the electric parking brake manually.
If the red !indicator lamp continues to flash:
X Do not drive on.
X Secure the vehicle against rolling away (Y page 439).
X Vehicles with manual transmission: engage first gear.
X Vehicles with automatic transmission: shift the transmission
to P.
X Turn the front wheels towards the kerb.
X Consult a qualified specialist workshop. The yellow
!warning lamp lights up. The red !indicator
lamp flashes for about ten seconds after the electric parking brake
has been applied or released. It then goes out or remains lit.
The electric parking brake is malfunctioning.
X Switch off the ignition and turn it back on.
X Apply the electric parking brake.
If it is not possible to apply the electric parking brake:
X Vehicles with manual transmission: engage first gear.
X Vehicles with automatic transmission: shift the transmission
to P.
X Consult a qualified specialist workshop.
If it is not possible to release the electric parking brake manually:
X Release the electric parking brake automatically (Y page 209).
If the electric parking brake still cannot be released: X Consult a qualified specialist workshop. 320
Display
messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions !
Turn on the igni‐ Turn on the igni‐
tion to release tion to release
the parking brake the parking brake The red
!indicator lamp lights up.
You attempted to release the electric parking brake while the igni-
tion was switched off.
X Switch the ignition on. J
Check brake fluid Check brake fluid
level level There is insufficient brake fluid in the brake fluid reservoir.
In addition, the red Jwarning lamp lights up in the instrument
cluster and a warning tone sounds.
G WARNING
Braking efficiency may be impaired.
There is a risk of an accident. X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away (Y page 207).
X Consult a qualified specialist workshop.
X Do not top up the brake fluid. This does not correct the fault. #
Check brake pad Check brake pad
wear wear The brake pads/linings have reached their wear limit.
X Visit a qualified specialist workshop. Collision Preven‐
Collision Preven‐
tion Assist Plus tion Assist Plus
currently unavail‐ currently unavail‐
able See Owner's able See Owner's
Manual Manual COLLISION PREVENTION ASSIST PLUS is temporarily inoperative.
Possible causes:
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio sta-
tions or other sources of electromagnetic radiation
R the system is outside the operating temperature range
R the on-board voltage is too low
Once the causes listed above no longer apply, the display message goes out.
COLLISION PREVENTION ASSIST PLUS 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 207).
X Restart the engine. 322
Display
messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions Collision Preven‐
Collision Preven‐
tion Assist Plus tion Assist Plus
inoperative inoperative COLLISION PREVENTION ASSIST PLUS is temporarily inoperative
due to a malfunction. Adaptive Brake Assist may also have failed.
X Visit a qualified specialist workshop. PRE-SAFE inopera‐
PRE-SAFE inopera‐
tive See Owner's tive See Owner's
Manual Manual
Important functions of PRE-SAFE
®
have failed. All other occupant
safety systems, e.g. airbags, remain available.
X Visit a qualified specialist workshop immediately. PRE-SAFE
PRE-SAFE
Functions
Functions
currently limited
currently limited
See Owner's Manual See Owner's Manual PRE
‑SAFE ®
PLUS or PRE ‑SAFE®
Brake is temporarily inoperative.
Possible causes:
R the function is impaired due to heavy rain or snow
R the radar sensor system is temporarily inoperative, e.g. due to
electromagnetic radiation emitted by nearby TV or radio sta-
tions or other sources of electromagnetic radiation
R the system is outside the operating temperature range
R the on-board voltage is too low
Once the causes listed above no longer apply, the display message
goes out.
PRE ‑SAFE ®
PLUS and PRE ‑SAFE®
Brake are 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 207).
X Restart the engine. PRE-SAFE PRE-SAFE
Functions
Functions
limited See Own‐
limited See Own‐
er's Manual er's Manual PRE
‑SAFE ®
PLUS or PRE‑ SAFE®
Brake is unavailable due to a mal-
function. BAS PLUS might also be deactivated.
X Visit a qualified specialist workshop. Display
messages
323On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions Radar sensors
Radar sensors
dirty See Owner's dirty See Owner's
Manual Manual At least one of the following driving systems or driving safety sys-
tems is temporarily restricted or inoperative:
R PRE-SAFE ®
PLUS
R PRE-SAFE ®
Brake
R COLLISION PREVENTION ASSIST PLUS
R Active Lane Keeping Assist
R Active Blind Spot Assist
R DISTRONIC PLUS
Possible causes:
R the sensors in the radiator trim and/or in the bumpers are dirty
R the function of the driving system and/or driving safety system
is impaired due to heavy rain or snow
A warning tone also sounds.
Once the causes listed above no longer apply, the display message
goes out. All driving systems/driving safety systems are operative 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 207).
X Switch off the engine.
X Clean the sensors (Y page 401) in the following locations:
R in the radiator trim
R in the front bumper
R in the rear bumper, particularly in the middle of the rear
bumper
X Restart the engine.
The display message disappears. ü ü If this symbol appears in the multifunction display, a seat belt
tongue has been inserted into a rear seat belt buckle.
Further information on the status indicator for the rear seat belts
(Y page 50). 324
Display
messagesOn-board computer and displays

Display messages
Possible causes/consequences and
M
MSolutions Front-passenger
Front-passenger
airbag disabled airbag disabled
See Owner's Manual See Owner's Manual The front-passenger front airbag is disabled during the journey
although:
R an adult
or
R a person larger than a certain size is occupying the front-
passenger seat
If additional forces are applied to the seat, the weight the system
detects may be too low.
G WARNING
The front-passenger front airbag does not deploy during an acci-
dent.
This poses an increased risk of injury. 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 207).
X Switch the ignition off.
X Have the occupant on the front-passenger seat step out of the
vehicle.
X Make sure that the seat is unoccupied, close the front-
passenger door and switch on the ignition.
X Observe the PASSENGER AIRBAG indicator lamps in the centre
console and the multifunction display and check the following:
Seat unoccupied and ignition switched on:
R the PASSENGER AIR BAG OFF and PASSENGER AIR BAG ON
indicator lamps must light up simultaneously for approx-
imately six seconds.
R the PASSENGER AIRBAG OFF indicator lamp must then light
up and remain lit. If the indicator lamp is on, the automatic
front-passenger front airbag deactivation system has disa-
bled the front-passenger front airbag (Y page 54).
R the display messages Front-passenger
Front-passenger airbag airbagenabled
enabled
See
See Owner's
Owner's Manual
ManualorFront-passenger
Front-passenger airbag
airbag disa‐
disa‐
bled See Owner's Manual
bled See Owner's Manual must not appear in the multi-
function display.
X Wait for a period of at least 60 seconds until the necessary sys-
tem checks have been completed.
X Make sure that the display messages do not appear in the mul-
tifunction display.
If these conditions are met, the front-passenger seat can be occu- pied again. Whether the PASSENGER AIRBAG OFF or ON indicator
lamp remains lit or goes out depends on how the automatic front- Display
messages
327On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions passenger front airbag deactivation system classifies the occu-
pant.
If the conditions are not met, the system is not operating correctly.
X Visit a qualified specialist workshop immediately.
Further information on the automatic front-passenger front airbag deactivation feature (Y page 54).Front-passenger Front-passenger
airbag airbag
enabled
enabled See
See
Owner's Manual
Owner's Manual The front-passenger front airbag is enabled during the journey
although:
R a child, a small adult or an object weighing less than the system
weight threshold is located on the front-passenger seat
or
R the front-passenger seat is not occupied
The system may detect objects or forces that are adding to the
weight applied to the seat.
G WARNING
The airbag may deploy unintentionally.
This poses an increased risk of injury. 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 207).
X Switch the ignition off.
X Open the front-passenger door.
X Remove the child and the child restraint system from the front-
passenger seat.
X Make sure there are no objects applying additional force to the
seat.
The system may otherwise detect the additional force and inter- pret the seat occupant's weight as greater than it actually is.
X Make sure that the seat is unoccupied, close the front-
passenger door and switch on the ignition.
X Observe the PASSENGER AIRBAG indicator lamps in the centre
console and the multifunction display and check the following:
Seat unoccupied and ignition switched on:
R the PASSENGER AIR BAG OFF and PASSENGER AIR BAG ON
indicator lamps must light up simultaneously for approx-
imately six seconds.
R the PASSENGER AIRBAG OFF indicator lamp must then light
up and remain lit. If the indicator lamp is on, the automatic 328
Display
messagesOn-board computer and displays

Engine
Display messages
Possible causes/consequences and
M
MSolutions +
Top Top
up
upcoolant
coolant See
See
Owner’s Manual
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 393).
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 putting the engine under heavy load as you do so, e.g.
driving in mountainous terrain and stop-start traffic. ?
Coolant Stop vehi‐ Coolant Stop vehi‐
cle Switch engine cle Switch engine
off 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.
In addition, 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 to prevent it from rolling away (Y page 207).
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 †. Display messages
333On-board computer and displays Z

Display messages
Possible causes/consequences and
M
MSolutions #
See Owner's Manual See Owner's Manual The battery is not being charged.
A warning tone also sounds.
Possible causes:
R faulty alternator
R defective power electronics (hybrid vehicles)
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.
! Do not continue driving. The engine could otherwise overheat.
X Secure the vehicle to prevent it from rolling away (Y page 207).
X Consult a qualified specialist workshop. #
Stop vehicle See Stop vehicle See
Owner's Manual Owner's Manual The battery is no longer being charged and the battery charge level
is too low.
A warning tone also sounds.
X Stop the vehicle immediately, paying attention to road and traf-
fic conditions, and switch off the engine.
X Secure the vehicle to prevent it from rolling away (Y page 207).
X Observe the instructions in the #See Owner's Manual See Owner's Manual
display message.
X Consult a qualified specialist workshop. #
Start engine See Start engine See
Owner's Manual Owner's Manual The engine is off and the battery charge level is too low.
X Switch off electrical consumers that you do not need, such as
the rear window heating and interior lighting.
X Leave the engine running for a few minutes, or drive for a longer
distance.
The battery charges. 334
Display
messagesOn-board computer and displays