2012 MERCEDES-BENZ B-CLASS o2 sensor

Display messages Possible causes/consequences and
M SolutionsPark Assist
Inoperative You have just carried out a large number of turning or parking
maneuvers.
Active Parking Assist will become available again after
approximately ten minutes (
Y page 172).
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Switch off and restart the engine.
If the display message continues to be displayed:
X Visit a qualified specialist workshop. PARKTRONIC is defective.
X
Visit a qualified specialist workshop. DISTRONIC PLUS Off DISTRONIC PLUS has been deactivated (
Y page 159). 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 159). DISTRONIC PLUS
Currently
Unavailable See
Operator's Manual DISTRONIC PLUS is temporarily inoperative. Possible causes are:
R
function is impaired due to heavy rain or snow.
R the sensors in the radiator trim 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.
A warning tone also sounds.
When the causes stated above no longer apply, the display
message disappears.
DISTRONIC 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 149).
X Clean the sensors in the radiator trim (Y page 275).
X Restart the engine. Display messages
217
On-board computer and displays Z
ProCarManuals.com

Engine
Problem Possible 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
R in the fuel system
The emission limit values may be exceeded and the engine may
be running in emergency mode.
X Have 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 depends on the locally applicable legal
requirements. If in doubt, check whether such legal regulations
apply in the state in which you are currently driving. æ
The yellow reserve fuel
warning lamp lights up
while the engine is
running.
The fuel level has dropped into the reserve range.
X
Refuel at the nearest gas station. æ
The yellow reserve fuel
warning lamp flashes
while the engine is
running.
The fuel system pressure is too low. The fuel filler cap is not closed
correctly or the fuel system is leaking.
X
Check that the fuel filler cap is correctly closed.
X If the fuel filler cap is not correctly closed:
close the

fuel filler
cap.
X If the fuel filler cap is closed: visit a qualified specialist
workshop. ?
The red coolant
warning lamp lights up
while the engine is
running and
the

coolant
temperature gage is at
the start of the scale. The temperature sensor for the coolant temperature gage is
defective.
The coolant
temperature
is no longer being monitored. There is a
risk of engine damage if the coolant temperature is too high.
X Pull over and stop the vehicle safely and switch off the engine,
paying attention to

road and traffic conditions. Do not continue
driving under any circumstances.
X Secure the vehicle against rolling away ( Y page 149).
X Consult a qualified specialist workshop. Warning and indicator lamps in the instrument cluster
231
On-board computer and displays Z
ProCarManuals.com

Cleaning the mirror turn signals
!
Only use cleaning agents or cleaning
cloths that are suitable for plastic lenses.
Unsuitable cleaning agents or cleaning
cloths could scratch
or damage the plastic
lenses of the mirror turn signals.
X Clean the plastic lenses of the mirror turn
signals in the

exterior mirror housing using
a wet sponge and a mild cleaning agent,
e.g. Mercedes-Benz car shampoo or
cleaning cloths.
Cleaning the sensors !
If you clean the sensors with a power
washer, make sure that you keep a
distance of at

least 11.8 in (30 cm) between
the vehicle and the power washer nozzle.
Information about the correct distance is
available from the equipment
manufacturer. X
Clean sensors : of the driving systems
with water, car shampoo and a soft cloth.
Cleaning the rear view camera !
Do not
clean

the camera lens and the area
around the rear view camera with a power
washer. X
Use clear water and a soft cloth to clean
camera lens :.
Cleaning the exhaust pipe !
Do not clean the exhaust pipe with acid-
based cleaning agents such as sanitary
cleansers or wheel cleaners.
X Clean the exhaust pipe with a care product
tested and approved by Mercedes-Benz.
Impurities combined with the effects of road
grit and corrosive

environmental factors may
cause flash rust to form on the surface. You
can restore the original shine of the exhaust
pipe by cleaning it regularly, especially in
winter and after washing. Interior care
Cleaning the display !
For cleaning, do not use any of the
following:
R alcohol-based thinner or gasoline
R abrasive cleaning agents
R commercially-available household
cleaning agents
These may damage

the display surface. Do
not put pressure on the display surface
when cleaning. This could lead to
irreparable damage to the display. Care
275
Maintenance and care Z
ProCarManuals.com

i
Use antifreeze/corrosion inhibitor
according to MB approval 325.0 or 326.0. Windshield washer system and
headlamp cleaning system
Important safety notes G
WARNING
Windshield washer concentrate is highly
flammable. If it comes into contact with hot
engine components or the exhaust system it
could ignite. There is a risk of fire and injury.
Make sure that no windshield washer
concentrate is spilled next to the filler neck.
! Only use washer fluid that is suitable for
plastic lamp lenses, e.g. MB SummerFit or
MB WinterFit. Unsuitable washer fluid
could damage the plastic lenses of the
headlamps.
! Do not add
distilled or de-ionized water to
the washer fluid container. Otherwise, the
level sensor may be damaged.
! Only MB SummerFit and MB WinterFit
washer fluid should be mixed together. The
spray nozzles may otherwise become
blocked.
When handling washer fluid, observe the
important safety notes on service products
(Y page 329).
At temperatures above freezing:
X Fill the washer fluid reservoir with a mixture
of water and windshield washer fluid, e.g.
MB SummerFit.
Add 1 part MB SummerFit to 100 parts water. At temperatures below freezing:
X
Fill the washer fluid reservoir with a mixture
of water and washer fluid, e.g. MB
WinterFit.
Adapt the mixing ratio to the outside
temperature.
R Down to 14 ‡ (Ò

10 †): mix 1 part MB
WinterFit with 2 parts water.
R Down to Ò4 ‡ (Ò20 †): mix 1 part MB
WinterFit with 1 part water.
R Down to Ò20.2 ‡ (Ò29 †): mix 2 parts MB
WinterFit with 1 part water.
i Add windshield washer fluid, e.g. MB
SummerFit or MB WinterFit, to the washer
fluid all year round. Climate control system refrigerant
Important safety notes Type of refrigerant
The instruction label about types of
refrigerants can be found on the radiator
cross member.
Refrigerant R-134a
!
Only use refrigerant R-134a and PAG oil
(part number A0019890803) which has
been approved by Mercedes-Benz. The
approved R-134a PAG

oil may not be mixed
with other conventional PAG oils.
Otherwise, the climate control system may
be damaged.
Service work, such as topping-up refrigerant
or replacing components, may only be carried
out by a qualified specialist workshop. All
applicable regulations must be adhered to,
SAE standard J639 included.
Always have work on the climate control
system carried out at a qualified specialist
workshop. 334
Service products and filling capacitiesTechnical data
ProCarManuals.com