2016 MERCEDES-BENZ C CLASS ECU

Display messages
Possible causes/consequences and P Solutions
The yellow $ warning lamp lights up and th e red I (US A only)
or $ (Canada only) indicator lamp flashes .
It is no t possibl e to apply th e electric parking brak e manually.X
Shift th e transmission to position P .X
Visit a qualified specialist workshop .
' (USA
only)
M ( Canada
only)
Check Brake Fluid
Level There is no t enough brak e flui d in th e brak e fluid reservoir .
In addition , th e ' (US A only) or M (Canada only) warning lamp
lights up in th e instrumen t cluste r and a warning tone sounds.
G WARNIN G
The braking effec t may be impaired.
There is a ris k of an accident.X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions. Do no t continu e drivin g
under any circumstances. X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Consult a qualified specialist workshop .X
Do no t add brak e fluid . This does no t correc t th e malfunction .
& Check Brake Pad Wea r The brak e pads/linings hav e reached their wear limit.
US A only: th e ' red brak e system warning lamp is lit while th e
engin e is running. X
Visit a qualified specialist workshop .
S Inoperative On e or mor e main features of th e mbrace system are malfunctioning .X
Visit a qualified specialist workshop .
Collision Preven ‐
tio n Assist Plu s
Currently Unavaila‐
ble See Operator' s
Manual COLLISION PREVENTION ASSIST PLU S is temporarily no t operational.
Possibl e causes are: R
th e radar sensor system is temporarily inoperative, e.g. due to elec -
tromagneti c radiation emitted by nearby TV or radi o station s or
other source s of electromagneti c radiation .R
th e system is outside th e operating temperature range.R
th e on-boar d voltag e is to o low.
Whe n th e causes state d abov e no longer apply, th e display message
disappears.
COLLISION PREVENTION ASSIST PLU S is operational again .
If th e display message does no t disappear :X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Restart th e engine. Display messages 26 1
On-board computer and displays Z

Display messages
Possible causes/consequences and P Solutions
Collision Preven ‐
tio n Assist Plu s
Inoperative COLLISION PREVENTION ASSIST PLU S is temporarily inoperative due
to a malfunction . Adaptive Brake Assis t may also hav e failed.X
Visit a qualified specialist workshop immediately.
PRE-SAFE Inopera‐
tiv e See Operator' s
Manual Importan t function s of PRE-SAF E ®
hav e failed. Al l other occupant
safet y systems , e.g. air bags , remain available.X
Visit a qualified specialist workshop immediately.
PRE-SAFE Functions
Currently Limite d
See Operator' s Man ‐
ual PRE ‑ S AF E ®
PLU S or PRE ‑ SAFE ®
Brake is temporarily inoperative.
Possibl e causes are: R
function is impaire d due to heav y rain or snow.R
th e radar sensor system is temporarily inoperative, e.g. due to elec -
tromagneti c radiation emitted by nearby TV or radi o station s or
other source s of electromagneti c radiation .R
Mercedes-AMG vehicles: ES P ®
is deactivatedR
th e system is outside th e operating temperature range.R
th e on-boar d voltag e is to o low.
Whe n th e causes state d abov e no longer apply, th e display message
disappears.
PRE ‑ S AF E ®
PLU S and PRE ‑ S AF E ®
Brake are operational again .
If th e display message does no t disappear :X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Restart th e engine.X
Mercedes-AMG vehicles: switch ES P ®
on again ( Y
page 74) .
PRE-SAFE Functions
Limite d See Opera‐
tor's Manual PRE ‑ S AF E ®
PLU S or PRE ‑ SAFE ®
Brake is unavailable due to a mal-
function . BA S PLU S wit h Cross-Traffic Assis t may also hav e failed.X
Visit a qualified specialist workshop immediately.262
Display messages
On-board computer and displays

Display messages
Possible causes/consequences and P Solutions
Radar Sensor s Dirty
See Operator' s Man ‐
ual At least on e of th e followin g drivin g systems or drivin g safet y systems
is temporarily restricted or inoperative: R
PRE-SAF E ®
PLU SR
PRE-SAF E ®
BrakeR
COLLISION PREVENTION ASSIST PLU SR
Active Lan e Keepin g Assis tR
Active Blind Spot Assis tR
DISTRONI C PLU S wit h Steering Assis t and Stop&Go Pilo t
If th e radar sensor system in fron t is dirty, Active Blind Spot Assis t will
no t perfor m a course-correcting brak e application .
Possibl e causes are: R
th e sensor s in th e radiato r trim and/o r in th e bumpers are dirtyR
th e function of th e drivin g system or drivin g safet y system is
impaire d due to heav y rain or snow
A warning tone also sounds.
Whe n th e causes state d abov e no longer apply, th e display message
disappears. Al l drivin g systems or drivin g safet y systems are operative
again .
If th e display message does no t disappear :X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Switc h off th e engine.X
Clean th e sensor s in th e followin g location s ( Y
page 339):R
in th e radiato r trimR
in th e fron t bumper R
in th e rear bumper, particularly in th e middle of th e rear bumperX
Restart th e engine.
The display message disappears.
u SRS Malfunction Ser ‐
vic e Required The restrain t system is faulty. The u warning lamp also lights up in
th e instrumen t cluster.
G WARNIN G
The air bags or Emergency Tensioning Devices may either be triggered
unintentionally or, in th e event of an accident, may no t be triggered .
There is an increased ris k of injury.X
Visit a qualified specialist workshop immediately.
Fo r further information about th e restrain t system, see ( Y
page 46) .Display messages 26 3
On-board computer and displays Z

Display messages
Possible causes/consequences and P Solutions
Front Passenger Air ‐
bag Disabled See
Operator' s Manual The front-passenger air bag is deactivated during th e journey, eve n
though : R
an adult
or R
a person of th e correspondin g statur e is on th e front-passenger seat
If additional force s are applie d to th e seat , th e system may interpret
th e occupant's weigh t as lower than it actually is.
G WARNIN G
The front-passenger air bag does no t deploy during an accident.
There is an increased ris k of injury.X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Switc h th e ignition off .X
Hav e th e occupant get out of th e vehicle.X
Kee p th e seat unoccupied , close th e front-passenger door and
switch on th e ignition .X
Observ e th e PASSENGER AI R BA G indicator lamp s in th e center
console and th e multifunction display and chec k th e following:
Seat unoccupied and ignition switched on :R
a self-diagnosis is carrie d out . The PASSENGER AI R BA G OF F and
PASSENGER AI R BA G ON indicator lamp s mus t ligh t up simulta-
neousl y for approximately six seconds R
th e PASSENGER AI R BA G OF F indicator lamp mus t then ligh t up
and remain lit after th e self-di agnosis . If th e indicator lamp is on ,
OCS (Occupant Classification System) has disabled th e front-
passenger fron t air bag ( Y
page 54 )R
th e display message s Front Passenger Airbag Enable d
See Operator' s Manual or Front Passenger Airbag Dis ‐
abled See Operator' s Manual mus t no t appear in th e multi-
function display X
Wait for a period of at least 60 seconds until th e necessar y system
checks hav e been completed.X
Mak e sur e that th e display message s do no t appear in th e multi-
function display.
If these condition s are fulfilled , th e front-passenger seat can be occu-
pied again . Whether th e PASSENGER AI R BA G OF F or ON indicator
lamp remain s lit or goe s out depend s on how OCS classifies th e occu-
pant.
If th e condition s are no t fulfilled , th e system is no t operating correctly.X
Visit a qualified specialist workshop immediately.
Fo r further information about th e Occupant Classification System, see
( Y
page 54). Display messages 26 5
On-board computer and displays Z

Display messages
Possible causes/consequences and P Solutions
Front Passenger Air ‐
bag Enable d See
Operator' s Manual The front-passenger air bag is enabled during th e journey, eve n
though : R
a child, a small adult or an objec t weighing less than th e system' s
weigh t threshold is locate d on th e front-passenger seat
or R
th e front-passenger seat is unoccupied
The system may detec t objects or force s applyin g additional weigh t on
th e seat .
G WARNIN G
The air bag may deploy unintentionally.
There is an increased ris k of injury.X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Switc h th e ignition off .X
Ope n th e front-passenger door .X
Remove th e child and th e child restrain t system from th e front-
passenger seat .X
Mak e sur e that there are no objects on th e seat addin g to th e
weight.
The system may otherwise detec t th e additional weigh t and inter-
pre t th e seat occupant's weigh t as greate r than it actually is.X
Kee p th e seat unoccupied , close th e front-passenger door and
switch on th e ignition .X
Observ e th e PASSENGER AI R BA G indicator lamp s in th e center
console and th e multifunction display and chec k th e following:
Seat unoccupied and ignition switche d on :R
a self-diagnosis is carrie d out . The PASSENGER AI R BA G OF F and
PASSENGER AI R BA G ON indicator lamp s mus t ligh t up simulta-
neousl y for approximately six seconds R
th e PASSENGER AI R BA G OF F indicator lamp mus t then ligh t up
and remain lit after th e self-diagnosis . If th e indicator lamp is on ,
OCS has disabled th e front-passenger fron t air bag ( Y
page 54)R
th e display message s Front Passenger Airbag Enable d
See Operator' s Manual or Front Passenger Airbag Dis ‐
abled See Operator' s Manual mus t no t appear in th e multi-
function display X
Wait for a period of at least 60 seconds until th e necessar y system
checks hav e been completed.X
Mak e sur e that th e display message s do no t appear in th e multi-
function display.
If these condition s are fulfilled , th e front-passenger seat can be occu-
pied again . Whether th e PASSENGER AI R BA G OF F or ON indicator
lamp remain s lit or goe s out depend s on how OCS classifies th e occu-
pant.
If th e condition s are no t fulfilled , th e system is no t operating correctly.266
Display messages
On-board computer and displays

Display messages
Possible causes/consequences and P Solutions
= Sto p Vehicl e See
Operator' s Manual The battery is no longer bein g charged and th e battery charg e level is
to o low.
A warning tone also sounds. X
Pull ove r and stop th e vehicl e safely and switch off th e engine, pay-
ing attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Observ e th e instruction s in th e = See Operator' s Manual
display message .X
Consult a qualified specialist workshop .
= Sto p Vehicl e Leave
Engine Runnin g The battery charg e level is to o low.X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions. Do no t continu e drivin g
under any circumstances. X
Leav e th e engin e running.X
Wait until th e display message disappear s before pullin g away.
= Start Engine See
Operator' s Manual The engin e is switched off and th e battery charg e level is to o low.X
Switc h off electrical consumer s that you do no t need, suc h as th e
rear window defroste r and interior lighting .X
Leav e th e engin e runnin g for a few minute s or drive a lon g distance.
The battery is bein g charged.

Hybrid drive system Display messages
Possible causes/consequences and P Solutions
r Vehicle Operational
Switch the Ignition
Off Before Exiting PLUG-IN HYBRID vehicles:
You are exiting the vehicle when it is in a ready-to-drive state. The
READY indicator in the multifunction display is on. A warning tone also
sounds.
If you leave the vehicle: X
Secure the vehicle against rolling away ( Y
page 177).X
Switch off the ignition and remove the SmartKey.
If you do not leave the vehicle: X
Switch off the electrical consumers, e.g. automatic climate control,
seat heating.
Please note the following: The electrical consumers are supplied by
the 12 V battery. If the vehicle is left in a ready-to-drive state for an
extended period, it will switch off once the 12 V battery is almost
empty. It will then only be possible to start the vehicle using a second
battery (jump-starting).
Change the current
drive program
before changing the
operating mode. or
Exit manual drive
program M before
changing the operat‐
ing mode. PLUG-IN HYBRID vehicles:
You have attempted to change the operating mode in the automatic
drive program S (Sport), S+ (Sport Plus) or in the manual drive pro-
gram M . X
Activate drive program C (Comfort) or E (Economy) ( Y
page 229).X
Select the preferred operating mode HYBRID , E-MODE , E-SAVE or
CHARGE ( Y
page 226).
E-MODE Currently
Unavailable PLUG-IN HYBRID vehicles:
The condition of charge of the high-voltage battery has dropped to the
lower limit and the E-MODE operating mode has been switched off.
Driving with the internal combustion engine is activated and the oper-
ating mode switches to the basic HYBRID setting.X
Continue driving using the internal combustion engine.
You can switch to the E-SAVE or CHARGE operating mode as
required ( Y
page 226).
If you select CHARGE , the high-voltage battery is charged.
Once the charge level display for the high-voltage battery has
increased slightly, you can switch to the E-MODE operating mode
again.272
Display messages
On-board computer and displays

Display messages
Possible causes/consequences and P Solutions
Onl y E-MODE Availa ‐
ble Power Limite d
Refuel Immediately PLUG-I N HYBRID vehicles:
The fuel tan k has been run dry and th e combustion engin e has been
switched off .
A warning tone also sounds.
The vehicl e will be powered by electrical energ y only. Performance is
restricted and th e vehicl e may accelerate mor e slowly than normal.X
Refue l at th e neares t gas station without fail .
In th e "Total range and electric range" menu, you can display th e
approximat e range of th e vehicl e ( Y
page 228).
Engine wil l not
restar t Servic e
required You canno t start th e engin e again due to a malfunction .
A warning tone also sounds.
If th e engin e is running: X
Visit a qualified specialist workshop .
If you switch off th e engine:X
Secur e th e vehicl e against rollin g away ( Y
page 177).X
Notify a qualified specialist workshop or breakdown service.
á Towing Not Permit ‐
ted See Operator' s
Manual The hybrid drive system is faulty. X
Hav e th e vehicl e transporte d on a transporte r or trailer to th e near-
est qualified specialist workshop .