check engine MERCEDES-BENZ B-Class 2017 W246 User Guide

X
Reach into the gap between the hood and the
radiator trim and press hood catch lever 0044to
the left.
X Raise the hood. X
Pull support strut 0085out of bracket 0083.
X Lift up support strut 0085and insert it into yel-
low retaining clip 0087.
Closing the hood X
Raise the hood slightly and, at the same time,
remove support strut 0085from yellow retaining
clip 0087.
X Swing support strut 0085down and press it into
bracket 0083until it engages.
X Lower the hood and let it fall from a height of
approximately 8 in (20 cm).
X Check that the hood has engaged properly.
If the hood can be raised slightly, it is not
properly engaged. Do not press the hood
closed. Open the hood again and close it with a little more force. Checking and adding other service
products
Checking coolant level G
WARNING
The cooling system is pressurized, particularly when the motor is warm. If you open the cap, you could be scalded if hot coolant sprays out.
There is a risk of injury.
Let the engine cool down before you open the
cap. Wear gloves and eye protection. Slowly
open the cap to relieve pressure. !
The coolant may only be checked and cor-
rected when the engine is cool (coolant tem-
perature below 104 ‡ (40 †).Checking the
coolant when the coolant temperature is
above 104 ‡ (40 †) may result in damage to
the engine or to the engine cooling system. X
Park the vehicle on a level surface.
Only check the coolant level when the vehicle
is on a level surface and the drive system has
cooled down.
X Turn the SmartKey to position 2in the ignition
lock (Y page 109).
X Check the coolant temperature display in the
instrument cluster.
The coolant temperature must be below
104 ‡ (40 †).
X Turn the SmartKey to position 0in the ignition
lock (Y page 109).
X Slowly turn cap 0043counter-clockwise to
relieve excess pressure.
X Turn cap 0043further counter-clockwise and
remove it.
If the coolant is at the level of marker bar 0087
in the filler neck when cold, there is enough
coolant in coolant expansion tank 0044.
X If necessary, add coolant that has been tested
and approved by Mercedes-Benz.
X Replace cap 0043and turn it clockwise as far as
it will go.
For further information on coolant, see
(Y page 284).
Windshield washer system G
WARNING
Certain components in the engine compart-
ment may be very hot, e.g. the drive system
and radiator. Working in the engine compart-
ment poses a risk of injury. 232
Engine compartmentMaintenance and care

R
It is particularly important to observe the
described order when connecting and dis-
connecting the jumper cables.
R Never connect or disconnect the battery
terminals while the engine is running. G
WARNING
Battery acid is caustic. There is a risk of injury. Avoid contact with skin, eyes or clothing. Do
not inhale any battery gases. Do not lean over
the battery. Keep children away from batter-
ies. Wash away battery acid immediately with
plenty of clean water and seek medical atten- tion. H
Environmental note Batteries contain dangerous
substances. It is against the
law to dispose of them with
the household rubbish. They
must be collected separately
and recycled to protect the
environment. Dispose of batteries in an
environmentally friendly
manner. Take discharged
batteries to a qualified spe-
cialist workshop or a special
collection point for used bat-
teries.
! Have the battery checked regularly at a
qualified specialist workshop.
Observe the service intervals in the Mainte-
nance Booklet or contact a qualified specialist workshop for more information.
Comply with safety precautions and take pro-
tective measures when handling batteries. Risk of explosion.
Fire, open flames and smoking are
prohibited when handling the bat-
tery. Avoid creating sparks. Battery acid is caustic. Avoid contact
with skin, eyes or clothing.
Wear suitable protective clothing,
especially gloves, apron and face-
guard.
Rinse any acid spills immediately
with clear water. Contact a physician if necessary. Wear eye protection.
Keep children away.
Observe this Operator's Manual.
For safety reasons, Mercedes-Benz recom-
mends that you only use batteries which have
been tested and approved for your vehicle by
Mercedes-Benz. These batteries provide
increased impact protection to prevent vehicle
occupants from suffering acid burns should the battery be damaged in the event of an accident.
In order for the battery to achieve the maximum possible service life, it must always be suffi-
ciently charged.
Like other batteries, the vehicle battery may
discharge over time if you do not use the vehicle.In this case, have the battery disconnected at a
qualified specialist workshop. You can also
charge the battery with a charger recommended by Mercedes-Benz. Contact a qualified special-
ist workshop for further information.
Have the battery condition of charge checked
more frequently if you use the vehicle mainly for
short trips or if you leave it standing idle for a
lengthy period. Consult a qualified specialist
workshop if you wish to leave your vehicle
parked for a long period of time.
Only replace a battery with a battery that has
been recommended by Mercedes-Benz.
Remove the SmartKey if you park the vehicle
and do not require any electrical consumers.
The vehicle will then use very little energy, thus conserving battery power.
After an interruption to the power supply, such
as due to a discharged battery, you must reset
the clock via the multimedia system. You can Batteries
247Breakdown assistance Z

find further information in the separate operat-
ing instructions. Charging the 12‑volt battery
G
WARNING
During charging and jump-starting, explosive
gases can escape from the battery. There is a risk of an explosion.
Particularly avoid fire, open flames, creating
sparks and smoking. Ensure there is sufficient
ventilation while charging and jump-starting.
Do not lean over a battery. G
WARNING
Battery acid is caustic. There is a risk of injury. Avoid contact with skin, eyes or clothing. Do
not inhale any battery gases. Do not lean over
the battery. Keep children away from batter-
ies. Wash away battery acid immediately with
plenty of clean water and seek medical atten- tion. G
WARNING
A discharged battery can freeze at tempera-
tures below freezing point. When jump-start-
ing the vehicle or charging the battery, gases can escape from the battery. There is a risk of
an explosion.
Allow the frozen battery to thaw out before
charging it or jump-starting.
! Only use battery chargers with a maximum
charging voltage of 14.8 V.
! Only
charge the battery using the jump-
starting connection point.
The jump-starting connection point is in the
engine compartment (Y page 249).
X Open the hood.
X Connect the battery charger to the positive
terminal and ground point in the same order
as when connecting the donor battery in the
jump-starting procedure (Y page 249).
If the indicator/warning lamps do not light up in
the instrument cluster at low temperatures, it is very likely that the discharged battery has fro-
zen. In this case you may neither jump-start the vehicle nor charge the battery. The service life of
a thawed-out battery may be shorter. The start-ing characteristics can be impaired, particularly at low temperatures. Have the thawed-out bat-
tery checked at a qualified specialist workshop.
Only charge the installed battery with a battery
charger which has been tested and approved byMercedes-Benz. A battery charger unit specially
adapted for Mercedes-Benz vehicles and tested
and approved by Mercedes-Benz is available as an accessory. It permits the charging of the bat-tery in its installed position. Contact an author-
ized Mercedes-Benz Center for further informa- tion and availability. Read the battery charger's
operating instructions before charging the bat-
tery. High-voltage battery – important
safety notes
G
DANGER
The vehicle's high-voltage electrical system is under high voltage. If you modify components
in the vehicle's high-voltage electrical system
or touch damaged components, you may be
electrocuted. The components in the vehi-
cle's high-voltage electrical system may be
damaged in an accident, although the damage is not visible. There is a risk of fatal injury.
Following an accident, do not touch any high- voltage components and never modify the
vehicle's high-voltage electrical system. Have
the vehicle towed away after an accident and
the vehicle's high-voltage electrical system
checked by a qualified specialist workshop. G
WARNING
In the event of a vehicle fire, the internal pres- sure of the high-voltage battery can exceed a
critical value. In this case flammable gas
escapes through a ventilation valve on the
underbody. The gas can ignite. There is a risk of injury.
Leave the danger zone immediately. Secure
the danger area at a suitable distance, whilst
observing legal requirements. 248
BatteriesBreakdown assistance

The vehicle's high voltage electrical system is
under high voltage.
R Do not handle high-voltage components or
the orange cables of the vehicle's high-volt-
age electrical system.
R Do not touch high-voltage components or the
orange cables of the high-voltage electrical
system when a vehicle has been involved in a
crash.
R Do not touch any damaged components or
the damaged orange cables of the vehicle's
high-voltage electrical system.
R Do not remove the covers of the high-voltage
electrical system components that are
marked with a warning sticker.
Do not leave the vehicle parked for longer than
14 days with a high-voltage battery condition of
charge below 20%.
You can check the condition of charge in the
charge level display (Y page 153). If you park the vehicle and leave it stationary for
longer periods, connect it to a power supply.
If you leave the vehicle parked for longer than
four weeks, the battery may be damaged by
exhaustive discharging.
If you leave the vehicle parked for longer than six weeks, the vehicle may suffer damage as a
result of lack of use.
X Visit a qualified specialist workshop and seek
advice.
i You can obtain information about trickle
chargers from a qualified specialist work-
shop.
i Very low or very high outside temperatures
can impair the function of the high-voltage
battery (Y page 119). This can also occur
when the vehicle engine is switched off
(Y page 119). Jump-starting
For the jump-starting procedure, use only the jump-starting connection point, consisting of a pos- itive terminal and a ground point, in the engine compartment. G
WARNING
Battery acid is caustic. There is a risk of injury.
Avoid contact with skin, eyes or clothing. Do not inhale any battery gases. Do not lean over the
battery. Keep children away from batteries. Wash away battery acid immediately with plenty of
clean water and seek medical attention. G
WARNING
During charging and jump-starting, explosive gases can escape from the battery. There is a risk of an explosion.
Particularly avoid fire, open flames, creating sparks and smoking. Ensure there is sufficient ven-
tilation while charging and jump-starting. Do not lean over a battery. G
WARNING
During the charging process, a battery produces hydrogen gas. If a short circuit occurs or sparks
are created, the hydrogen gas can ignite. There is a risk of an explosion.
R Make sure that the positive terminal of a connected battery does not come into contact with
vehicle parts.
R Never place metal objects or tools on a battery.
R It is important that you observe the described order of the battery terminals when connecting
and disconnecting a battery.
R When jump-starting, make sure that the battery poles with identical polarity are connected. Jump-starting
249Breakdown assistance
Z

R
It is particularly important to observe the described order when connecting and disconnecting
the jumper cables.
R Never connect or disconnect the battery terminals while the engine is running. G
WARNING
A discharged battery can freeze at temperatures below freezing point. When jump-starting the
vehicle or charging the battery, gases can escape from the battery. There is a risk of an explosion.
Allow the frozen battery to thaw out before charging it or jump-starting.
! Avoid repeated and lengthy starting attempts.
Do not use a rapid-charging device to start the engine.
If the indicator/warning lamps do not light up in the instrument cluster at low temperatures, it is very likely that the discharged battery has frozen. In this case you may neither jump-start the vehicle norcharge the battery. The service life of a thawed-out battery may be shorter. Have the thawed-out
battery checked at a qualified specialist workshop.
If the 12 V battery is discharged, or after the vehicle has been jump-started, the Service
Service
Required Required Do
DoNot
Not Shift
Shift Gears
GearsVisit
VisitDealer
Dealer message appears. There is a malfunction in the
on-board voltage. Visit a qualified specialist workshop immediately.
The drive system cannot be started if the 12 V battery is discharged. This is not dependent on
whether the high-voltage battery is charged or not. The vehicle cannot be jump-started if the high-
voltage battery is discharged. The high-voltage battery must be charged first.
The drive system can be started using another vehicle. R Only use batteries with an equal nominal voltage (12 volts).
R Make sure that the battery of the donor vehicle does not have a significantly lower capacity than
the discharged battery.
R Use jumper cables with a sufficient cross-section and insulated terminal clamps from a qualified
specialist workshop, e.g. an authorized Mercedes-Benz Center.
R Make sure that the two vehicles do not touch.
R Route the jumper cables so that they cannot be caught by rotating components in the engine
compartment.
R Do not disconnect the discharged battery from the vehicle's electrical system. 250
Jump-startingBreakdown assistance

wise, components or systems could be dam-
aged.
! Make sure that no moisture can enter the
fuse box when the cover is open.
! When closing the cover, make sure that it is
lying correctly on the fuse box. Moisture seep-
ing in or dirt could otherwise impair the oper- ation of the fuses.
The fuses in your vehicle serve to close down
faulty circuits. If a fuse blows, all the compo-
nents on the circuit and their functions stop
operating.
Blown fuses must be replaced with fuses of the same rating, which you can recognize by the
color and value. The fuse ratings are listed in the
fuse allocation chart.
The fuse allocation chart is in the fuse box in the front-passenger footwell (Y page 256).
If a newly inserted fuse also blows, have the
cause traced and rectified at a qualified special- ist workshop, e.g. an authorized Mercedes-Benz
Center. Before changing a fuse
X Secure the vehicle against rolling away
(Y page 128).
X Switch off all electrical consumers.
X Vehicles without KEYLESS-GO: remove the
SmartKey from the ignition lock.
X Vehicles with KEYLESS-GO: open the driv-
er's door.
The vehicle electronics now have status 0.
This is the same as the SmartKey having been removed.
The fuses are located in various fuse boxes: R Fuse box in the engine compartment on the
left-hand side of the vehicle, when viewed in
the direction of travel
R Fuse box in the front-passenger footwell
The fuse allocation chart is on the fuse box in the front-passenger footwell (Y page 256). Fuse box in the engine compartment
G
WARNING
When the hood is open and the windshield
wipers are set in motion, you can be injured by the wiper linkage. There is a risk of injury.
Always switch off the windshield wipers and
the ignition before opening the hood. X
Open the hood.
X Use a dry cloth to remove any moisture from
the fuse box.
X To open: unclip hood release cable 0085from
bracket 0087.
X Open retaining clamps 0044.
X Fold cover 0043up in the direction of the arrow
and remove it. X
To close: check whether the seal is seated
correctly in cover 0043.
X Insert cover 0043at the back into openings 0083
on the fuse box.
X Slide hood release cable 0085to the side and
hold if necessary.
X Fold down cover 0043.
X Clip hood release cable 0085into bracket 0087. Fuses
255Breakdown assistance Z

i
The coolant is checked with every mainte-
nance interval at a qualified specialist work-
shop.
Filling capacities Missing values were not available at time of
going to print. Model Capacity
All models
Windshield washer system
Important safety notes G
WARNING
Windshield washer concentrate could ignite if it comes into contact with hot engine compo-
nents or the exhaust system. There is a risk of
fire and injury.
Make sure that no windshield washer con-
centrate is spilled next to the filler neck.
! Only MB SummerFit and MB WinterFit
washer fluid should be mixed together. The
spray nozzles may otherwise become
blocked.
Do not use distilled or de-ionized water. Other-
wise, the level sensor may give a false reading.
When handling washer fluid, observe the impor- tant safety notes on service products
(Y page 283).
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.
For the correct mixing ratio refer to the infor- mation on the antifreeze reservoir.
i Add windshield washer fluid, e.g. MB Sum-
merFit or MB WinterFit, to the washer fluid all
year round. Climate control system refrigerant
Important safety notes The climate control system of your vehicle is fil-
led with refrigerant R‑ 134a.
The instruction label regarding the refrigerant
type used can be found on the left, on the under-
side of the hood.
! Only the refrigerant R‑134a and the PAG oil
approved by Mercedes-Benz may be used.
The approved PAG oil may not be mixed with
any other PAG oil that is not approved for
R-134a refrigerant. Otherwise, the climate
control system may be damaged.
Service work, such as refilling with refrigerant or replacing component parts, may only be carriedout by a qualified specialist workshop. All appli-
cable regulations, as well as SAE standard J639, must be adhered to.
Always have work on the climate control system
carried out at a qualified specialist workshop.
Refrigerant instruction label Example: refrigerant instruction label
0043 Warning symbol
0044 Refrigerant filling capacity
0087 Applicable standards
0085 PAG oil part number
0083 Type of refrigerant
Warning symbol 0043advises you about:
R Possible dangers
R Having service work carried out at a qualified
specialist workshop Service products and filling capacities
285Technical data Z