Sensors MERCEDES-BENZ C-Class SEDAN 2012 W204 User Guide

Warning displays
The warning displays show the distance
between the sensors and the obstacle. The
warning display for the front area is located
on the dashboard above the center air vents.
The warning display for the rear area is
located on the headliner in the rear
compartment.
Warning display for the front area
:Segments on the left-hand side of the
vehicle;Segments on the right-hand side of the
vehicle=Segments showing operational readiness
The warning display for each side of the
vehicle is divided into five yellow and two red
segments. PARKTRONIC is operational if
yellow segments showing operational
readiness = light up.
The selected transmission position
determines which warning display is active
when the engine is running.
Transmission
positionWarning displayDFront area activatedR , N or the vehicle
is rolling
backwardsRear and front areas
activatedPNo areas activatedOne or more segments light up as the vehicle
approaches an obstacle, depending on the
vehicle's distance from the obstacle.
From the:
R sixth segment onwards, you will hear an
intermittent warning tone for
approximately two seconds.
R seventh segment onwards, you will hear a
warning tone for approximately two
seconds. This indicates that you have now
reached the minimum distance.
Deactivating/activating PARKTRONIC:Indicator lamp;To deactivate/activate PARKTRONIC
If indicator lamp : lights up, PARKTRONIC is
deactivated. Parking Guidance is also
deactivated.
i PARKTRONIC is automatically activated
when you turn the SmartKey to position 2
in the ignition lock.
Driving systems177Driving and parkingZ

Problems with PARKTRONICProblemPossible causes/consequences and M SolutionsOnly the red segments
in the PARKTRONIC
warning displays are lit.
You also hear a warning
tone for approximately
two seconds.
PARKTRONIC is
deactivated after
approximately
20 seconds, and the
indicator lamp in the
PARKTRONIC button
lights up.PARKTRONIC has malfunctioned and has switched off.XIf problems persist, have PARKTRONIC checked at a qualified
specialist workshop.Only the red segments
in the PARKTRONIC
warning displays are lit.
PARKTRONIC is
deactivated after
approximately 20
seconds.The PARKTRONIC sensors are dirty or there is interference.XClean the PARKTRONIC sensors ( Y page 287).XSwitch the ignition back on.The problem may be caused by an external source of radio or
ultrasound waves.XSee if PARKTRONIC functions in a different location.Parking Guidance
Important safety notes
i Parking Guidance is only available in
Canada.
Parking Guidance is an electronic parking aid
with ultrasound. Ultrasound is used to
measure the road on both sides of the vehicle.
A suitable parking space is indicated by the
parking symbol. You receive steering
instructions when parking. You may also use
PARKTRONIC ( Y page 175).
GWARNING
Parking Guidance is merely an aid and may
display parking spaces that are not suitable
for parking, for example:
R no-parking areas
R parking spaces with unsuitable surfaces
(road surface)
R driveways
R entrances and exits
Parking Guidance detects and measures
potential parking spaces while driving past.
Changes to the parking space after this point
are not taken into account, for example if the
vehicle in front of or behind the parking space
changes position or objects in the parking
space are moved.
Even when using Parking Guidance, you are
still responsible for driving carefully. If you
rely on Parking Guidance alone, you could
178Driving systemsDriving and parking

The functionality of ATTENTION ASSIST is
restricted and warnings may be delayed or
not occur at all:
R if the road condition is poor, e.g. if the
surface is uneven or if there are potholes
R if there is a strong side wind
R if you have adopted a sporty driving style
with high cornering speeds or high rates of
acceleration
R if you predominantly drive at speeds under
50 mph (80 km/h) or over 112 mph
(180 km/h)
R if you are currently using COMAND or
making a telephone call with it
R if the time has been set incorrectly
R in active driving situations, such as when
you change lanes or change your speed
Warning and display messages in the
multifunction displayXActivate ATTENTION ASSIST using the on-
board computer ( Y page 205).
Symbol : appears in the multifunction
display.
If ATTENTION ASSIST is active, you will be
warned no sooner than 20 minutes after your
journey has begun. You will then hear an
intermittent warning tone twice, and the
Attention Assist: Drowsiness
Detected message appears in the
multifunction display.
XIf necessary, take a break.XPress a to confirm the message.
On long journeys, take regular breaks in good
time to allow yourself to rest properly. If you
do not take a break and ATTENTION ASSIST
still detects typical indicators of fatigue or
increasing lapses in concentration, you will be
warned again after 15 minutes at the earliest.
ATTENTION ASSIST is reset when you
continue your journey and starts assessing
your tiredness again if:
R you switch off the engine.
R you take off your seat belt and open the
driver's door, e.g. for a change of drivers or
to take a break.
Lane Tracking package
General notes
The Lane Tracking package consists of Blind
Spot Assist ( Y page 183) and Lane Keeping
Assist ( Y page 185).
Blind Spot Assist
Important safety notes
Blind Spot Assist uses a radar sensor system
to monitor the areas on both sides of your
vehicle. It supports you from speeds of
approximately 20 mph (30 km/h). A warning
display in the exterior mirrors draws your
attention to vehicles detected in the
monitored area. If you then switch on the
corresponding turn signal to change lane, you
will also receive an optical and audible
collision warning. Blind Spot Assist uses
sensors in the rear bumper for monitoring
purposes.
GWARNING
Blind Spot Assist is only an aid designed to
assist driving. It may fail to detect some
vehicles and is no substitute for attentive
driving.
Blind Spot Assist cannot detect road and
traffic conditions. It may fail to detect narrow
vehicles, such as motorcycles or bicycles, or
may only detect them too late.
Monitoring may be affected by dirty sensors,
strong spray or poor visibility caused by snow,
Driving systems183Driving and parkingZ

rain or mist, for example. In this case, vehicles
are detected late or not at all.
Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others.
i USA only:
This device has been approved by the FCC
as a “Vehicular Radar System”. The radar
sensor is intended for use in an automotive
radar system only. Removal, tampering, or
altering of the device will void any
warranties, and is not permitted by the
FCC. Do not tamper with, alter, or use in
any non-approved way.
Any unauthorized modification to this
device could void the user’s authority to
operate the equipment.
For Blind Spot Assist to assist you when
driving, the radar sensor system must be
activated ( Y page 208) and operational.
Monitoring range of the sensors
Blind Spot Assist monitors the area shown in
the figure up to 10 ft (3 m) behind and
immediately adjacent to your vehicle.GWARNING
Blind Spot Assist monitors certain areas in the
immediate vicinity of your vehicle. Vehicles
that approach and drive past at high speeds
are not detected. There is no display and no
warning.
If the lanes are very wide, it may not be
possible to monitor the complete width of the
neighboring lane. For this reason, vehicles in
the next lane may not be detected, especially
if they are driving in a staggered formation.
This may be the case if vehicles are driving at
that edge of their lane which is furthest away
from your vehicle.
Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others.
If the lanes are narrow, vehicles driving in the
lane beyond the lane next to your vehicle may
be indicated, especially if the vehicles are not
driving in the middle of their lane. This may
be the case if the vehicles are driving on the
inner side of their lane.
Due to the nature of the system:
R warnings may be issued in error when
driving close to crash barriers or similar
solid lane borders.
R warnings may be interrupted when driving
alongside long vehicles, such as trucks, for
a prolonged time.
The two sensors for Blind Spot Assist are
integrated into the sides of the rear bumper.
Make sure that the bumper is free from dirt,
ice or slush around the sensors. The rear
sensors must not be covered, for example by
bicycle racks or overhanging loads. Following
a severe impact or in the event of damage to
the bumpers, have the function of the radar
sensors checked at a qualified specialist
workshop, e.g. an authorized Mercedes-Benz
Center. Blind Spot Assist may otherwise not
work properly.184Driving systemsDriving and parking

Active Driving Assistance package
General notes
The Active Driving Assistance package
consists of DISTRONIC PLUS ( Y page 161),
Active Blind Spot Assist ( Y page 187) and
Active Lane Keeping Assist ( Y page 190).
Active Blind Spot Assist
Important safety notes
Active Blind Spot Assist uses a radar sensor
system to monitor the side areas of your
vehicle which are in back of the driver. A
warning display in the exterior mirrors draws
your attention to vehicles detected in the
monitored area. If you then switch on the
corresponding turn signal to change lane, you
will also receive an optical and audible
collision warning. If a risk of lateral collision
is detected, corrective braking may help you
avoid a collision. To support the course-
correcting brake application, Active Blind
Spot Assist also uses the forward-facing radar
sensor system. Active Blind Spot Assist
supports you from speeds of approximately
20 mph (30 km/h).
GWARNING
Active Blind Spot Assist is only an aid, and
may detect vehicles/obstacles incorrectly or
not at all.
The system may be impaired or may not
function if:
R there is poor visibility, e.g. due to snow,
rain, fog or spray.
R the rear and/or front sensors are dirty.
Active Blind Spot Assist may not detect
narrow vehicles, such as motorcycles or
bicycles, or may only detect them too late. It
cannot detect vehicles that are overtaken at
a small distance and then enter the blind spot
area.
Active Blind Spot Assist cannot detect road
and traffic conditions. It is not a substitute for
attentive driving. You are responsible for the
vehicle's speed, braking in good time, and
steering correctly. Always adapt your driving
style to suit the prevailing road and weather
conditions. Always pay attention to traffic
conditions and your surroundings. Otherwise,
you may fail to recognize dangers in time,
cause an accident and injure yourself and
others.
i USA only:
This device has been approved by the FCC
as a “Vehicular Radar System”. The radar
sensor is intended for use in an automotive
radar system only. Removal, tampering, or
altering of the device will void any
warranties, and is not permitted by the
FCC. Do not tamper with, alter, or use in
any non-approved way.
Any unauthorized modification to this
device could void the user’s authority to
operate the equipment.
For Active Blind Spot Assist to assist you
when driving, the radar sensor system must
be activated ( Y page 208) and operational.
Monitoring area
Active Blind Spot Assist monitors the area
shown in the figure up to 10 ft (3 m) behind
and immediately adjacent to your vehicle. For
this purpose, Active Blind Spot Assist uses
radar sensors in the rear bumper.Driving systems187Driving and parkingZ

GWARNING
Active Blind Spot Assist monitors certain
areas in the immediate vicinity of your vehicle.
Vehicles that approach and drive past at high
speeds are not detected. No visual nor
audible warnings are emitted and the system
does not brake the vehicle to correct your
course.
If the lanes are very wide, it may not be
possible to monitor the complete width of the
neighboring lane. For this reason, vehicles in
the next lane may not be detected, especially
if they are driving in a staggered formation.
This may be the case if vehicles are driving at
that edge of their lane which is furthest away
from your vehicle.
Always pay attention to traffic conditions and
your surroundings. Otherwise, you may fail to
recognize dangers in time, cause an accident
and injure yourself and others.
If the lanes are narrow, vehicles driving in the
lane beyond the lane next to your vehicle may
be indicated, especially if the vehicles are not
driving in the middle of their lane. This may
be the case if there are vehicles driving at the
inner edge of their lanes.
Due to the nature of the system:
R warnings may be issued in error when
driving close to crash barriers or similar
solid lane borders.
R warnings may be interrupted when driving
alongside long vehicles, such as trucks, for
a prolonged time.
Two Active Blind Spot Assist radar sensors
are integrated into the front and rear bumpers
respectively. An additional radar sensor is
located behind the cover in the radiator grill.
Make sure that the sensor areas on the
bumpers and the sensor cover in the radiator
grill are free of dirt, ice and slush. The rear
sensors must not be covered, for example by
cycle racks or overhanging cargo. Following
a severe impact or in the event of damage to
the bumpers, have the function of the radar
sensors checked at a qualified specialist
workshop. Blind Spot Assist may otherwise
not work properly.
Indicator and warning display:Yellow indicator lamp/red warning lamp
When Active Blind Spot Assist is activated,
indicator lamp : lights up yellow in the
exterior mirrors up to a vehicle speed of
20 mph (30 km/h). When the vehicle speed
exceeds 20 mph (30 km/h), the indicator
lamp goes out and Active Blind Spot Assist is
ready for use.
When your speed exceeds approximately
20 mph (30 km/h), warning lamp : lights up
red on the corresponding side whenever a
vehicle is detected in the blind spot
monitoring range. This warning is always
given when a vehicle enters the blind spot
monitoring range from behind or from the
side. When you are passing another vehicle,
the warning is emitted only if the difference
in speed is less than 7 mph (12 km/h).
The yellow indicator lamp goes out if reverse
gear is engaged. In this event, Active Blind
Spot Assist is no longer active.
The brightness of the indicator/warning
lamps is adjusted automatically according to
the ambient light.
GWARNING
Active Blind Spot Assist is not active at speeds
lower than 20 mph (30 km/h). The indicator
lamps in the exterior mirrors are yellow.
Vehicles in the monitoring range are then not
indicated.
188Driving systemsDriving and parking

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
Function Currently
Limited See Oper.
ManualGRisk of accident
PRE-SAFE ®
Brake is temporarily inoperative if:
R the DISTRONIC PLUS cover in the radiator grill is dirty.
R the sensors in the bumpers are dirty.
R its 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
stations or other sources of electromagnetic radiation.
R you switch off ESP ®
(AMG vehicles only).
R the system is outside the operating temperature range.
R the on-board voltage is too low.
PRE-SAFE ®
Brake is operational again and the display message
disappears if:
R the dirt (e.g. slush) drops away while the vehicle is in motion.
R the system detects that the sensors are fully available again.
R you switch ESP ®
on again (AMG vehicles only).
R the system is within the operating temperature range.
If the display message continues to be displayed:
XClean the DISTRONIC PLUS cover in the radiator grill
( Y page 287).XClean the bumpers ( Y page 287).XRestart the engine.XWait until the battery is sufficiently charged.PRE-SAFE
Functions Limited
See Operator's
ManualGRisk of accident
PRE-SAFE ®
Brake is defective. BAS PLUS or the distance warning
signal may also have failed.
XVisit a qualified specialist workshop.218Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M SolutionsRadar Sensors
Deactivated See
Operator's ManualThe radar sensor system is deactivated.XSwitch on the radar sensor system ( Y page 208).Lane Keeping
Assist Currently
Unavailable. See
Operator's Manual
or Lane Keeping
Assist Currently
Unavailable. See
Operator's ManualLane Keeping Assist or Active Lane Keeping Assist is deactivated
and temporarily inoperative if:
R the windshield is dirty in the camera's field of vision.
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, for example by dirt
or snow.
Lane Keeping Assist or Active Lane Keeping Assist is operational
again and the display message disappears if:
R the dirt (e.g. slush) drops away while the vehicle is in motion.
R the system recognizes that the camera is fully operational again.
If the display message continues to be displayed:XClean the windshield.Lane Keeping
Assist Inoperative
or Active Lane
Keeping Assist
InoperativeLane Keeping Assist or Active Lane Keeping Assist is defective.XVisit a qualified specialist workshop.Display messages229On-board computer and displaysZ

Display messagesPossible causes/consequences and M SolutionsBlind Spot Assist
Currently
Unavailable See
Operator's Manual
or Active Blind
Spot Assist
Currently
Unavailable See
Operator's ManualBlind Spot Assist or Active Blind Spot Assist is temporarily
inoperative if:
R the sensors are dirty.
R its 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.
Blind Spot Assist or Active Blind Spot Assist is operational again
and the display message disappears if:
R the dirt (e.g. slush) drops away while the vehicle is in motion.
R the system detects that the sensors are fully available again.
R the radar sensor system is back within the operating
temperature range.
If the display message continues to be displayed:XClean the sensors ( Y page 287).XRestart the engine.Blind Spot Assist
Inoperative or
Active Blind Spot
Assist InoperativeBlind Spot Assist or Active Blind Spot Assist is defective.
The yellow 9 indicator lamps also light up in the exterior
mirrors.XVisit a qualified specialist workshop.Parking Guidance
InoperativeParking Guidance is malfunctioning ( Y page 178).XRestart the engine.
If the display message continues to be displayed:
XVisit a qualified specialist workshop.230Display messagesOn-board computer and displays

Display messagesPossible causes/consequences and M SolutionsParking Guidance
CanceledParking Guidance has been deactivated because:
R the vehicle is skidding.
R the sensors are dirty.
R a malfunction has occurred.
A warning tone also sounds.XReactivate Parking Guidance later ( Y page 178).
If the parking space symbol is not displayed in the multifunction
display when you are driving at a speed of less than 19 mph
(30 km/h):
XClean the sensors ( Y page 287).XRestart the engine.
If the parking space symbol is still not displayed in the
multifunction display when you are driving at a speed of less than
19 mph (30 km/h):
XVisit a qualified specialist workshop.Parking Guidance has been deactivated because you are no longer
following the recommended path.XPark again and, while doing so, observe the display messages
in the multifunction display.Parking Guidance
FinishedThe vehicle is parked. A warning tone also sounds.
The display message disappears automatically.DISTRONIC PLUS
OffDISTRONIC PLUS has been deactivated ( Y page 161). 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 161).Display messages231On-board computer and displaysZ