lock MERCEDES-BENZ B-Class 2017 W246 Owner's Manual

Mercedes-Benz Customer Assistance Center
at 1-800-FOR-MERCedes (1-800-367-6372)
or 1-866-990-9007
You will be asked for your password.
X Return to your vehicle at the time agreed upon
with the Mercedes-Benz Customer Assis-
tance Center.
Alternatively, the vehicle can be opened via:
R the Internet, under the "Owners Online" sec-
tion
R telephone applications (e.g. for iPhone ®
,
Android™)
To do this, you will need your identification num-
ber and password.
Vehicle remote closing The vehicle remote-closing feature can be used
when you have forgotten to lock the vehicle and
you are no longer nearby.
The vehicle can then be locked by the Mercedes-
Benz Customer Assistance Center.
The vehicle can be immediately remotely locked within four days of the ignition being turned off.
After this time, remote closing may be delayed
by 15 to 60 minutes. After 30 days the vehicle
can no longer be valet locked remotely.
The vehicle remote closing feature is available if the relevant mobile phone network is available
and a data connection is possible.
X Contact the following service hotlines:
Mercedes-Benz Customer Assistance Center
at 1-800-FOR-MERCedes (1-800-367-6372)
or 1-866-990-9007
You will be asked for your password.
The next time you are inside the vehicle and you switch on the ignition, the Doors Locked
Doors Locked
Remotely Remotely message appears in the multifunction
display.
Alternatively, the vehicle can be locked via:
R the Internet, under the "Owners Online" sec-
tion
R telephone applications (e.g. for iPhone ®
,
Android™)
To do this, you will need your identification num- ber and password. Stolen vehicle recovery service If your vehicle has been stolen:
X Notify the police.
The police will issue a numbered incident
report.
X This number will be forwarded to the
Mercedes-Benz Customer Assistance Center
together with your PIN.
The Mercedes-Benz Customer Assistance
Center then tries to locate the system. The
Mercedes-Benz Customer Assistance Center
contacts you and the local law enforcement
agency if the vehicle is located.
However, only the law enforcement agency is informed of the location of the vehicle.
If the anti-theft alarm system is activated for
longer than 30 seconds, the Mercedes-Benz
Customer Assistance Center is automatically
notified.
Vehicle Health Check With the Vehicle Health Check, the Customer
Assistance Center can provide improved sup-
port for problems with your vehicle. During an
existing call, vehicle data is transferred to the
Customer Assistance Center.
The customer service representative can use
the received data to decide what kind of assis-
tance is required. You are then, for example,
guided to the nearest Mercedes-Benz Service
Center or a recovery vehicle is called.
If vehicle data needs to be transferred during an MB Info call or a Roadside Assistance call, this is
initiated by the Customer Assistance Center.
The Roadside Assistance Connected Roadside Assistance Connected mes-
sage appears in the display. If the Vehicle Health
Check can be started, the Request
Requestfor
forVehi‐
Vehi‐
cle Diagnostics Received Start vehi‐
cle Diagnostics Received Start vehi‐
cle diagnostics? cle diagnostics? message appears in the
display.
X Press the Yes
Yesbutton to confirm the message.
X When the Vehicle Diagnostics Please
Vehicle Diagnostics Please
Start Ignition
Start Ignition message appears: turn the
SmartKey to position 2in the ignition lock
(Y page 109).
X If the Please follow the instructions
Please follow the instructions
received
received by
byphone
phone and
andmove
move your
yourvehi‐
vehi‐
cle to a safe position.
cle to a safe position. message
appears: please follow the instructions 224
FeaturesStowage and features

Currently inactive areas can be activated by text
message.
Triggering the vehicle alarm With this function, you can trigger the vehicle's
panic alarm via text message. An alarm sounds
and the exterior lighting flashes. Depending on
the setting, the panic alarm lasts five or ten sec-
onds. Afterwards, the alarm switches off. Garage door opener
General notes The HomeLink
®
garage door opener integrated
in the rear-view mirror allows you to operate up to three different door and gate systems.
Use the integrated garage door opener only on
garage doors that:
R have safety stop and reverse features and
R meet current U.S. federal safety standards
Once programed, the integrated garage door
opener in the rear-view mirror will assume the
function of the garage door system's remote
control. Please also read the operating instruc-
tions for the garage door system.
When programming a garage door opener, park
the vehicle outside the garage. Do not leave the engine running while programming.
Certain garage door drives are incompatible
with the integrated garage door opener. If you
have difficulty programing the integrated garage
door opener, contact a Mercedes-Benz Service
Center.
Alternatively, you can call the following tele-
phone assistance services:
R USA: Mercedes-Benz Customer Assistance
Center at 1-800-FOR-MERCedes
R Canada: Customer Service at
1-800-387-0100
R HomeLink ®
hotline 1-800-355-3515 (free of
charge)
More information on HomeLink ®
and/or com-
patible products is also available online at
http://www.homelink.co m.
Notes on the declaration of conformity
(Y page 26).
USA: FCC ID: CB2HMIHL4
Canada: IC: 279B-HMIHL4 Important safety notes G
WARNING
When you operate or program the garage door with the integrated garage door opener, per-
sons in the range of movement of the garage
door can become trapped or struck by the
garage door. There is a risk of injury.
When using the integrated garage door
opener, always make sure that nobody is
within the range of movement of the garage
door.
Programming Programming the buttons
Pay attention to the "Important safety notes"
(Y page 226). Garage door remote control
0083is not included
with the integrated garage door opener.
X Turn the SmartKey to position 2in the ignition
lock (Y page 109).
X Select one of buttons 0044to0085 to control the
garage door drive.
X To start program mode: press and hold one
of buttons 0044to0085 on the integrated garage
door opener.
The garage door opener is now in program
mode. After a short time, indicator lamp 0043
lights up yellow.
Indicator lamp 0043lights up yellow as soon as
button 0044,0087or0085 is stored for the first time.
If the selected button has already been pro-
gramed, indicator lamp 0043will only light up
yellow after ten seconds have elapsed.
X Release button 0044,0087or0085. Indicator
lamp 0043flashes yellow. 226
FeaturesStowage and features

X
To program the remote control: point
garage door remote control 0083towards but-
tons 0044to0085 on the rear-view mirror at a dis-
tance of 2to 8 in (5 to 20 cm).
X Press and hold button 0084on remote control
0083 until indicator lamp 0043lights up green.
When indicator lamp 0043lights up green: pro-
gramming is finished.
When indicator lamp 0043flashes green: pro-
gramming was successful. The next step is to synchronize the rolling code (Y page 227).
X Release button 0084on remote control 0083for
the garage door drive system.
If indicator lamp 0043lights up red: repeat the
programing procedure for the corresponding
button on the rear-view mirror. When doing
so, vary the distance between remote control 0083 and the rear-view mirror.
The required distance between remote con-
trol 0083and the integrated garage door opener
depends on the garage door drive system.
Several attempts might be necessary. You
should test every position for at least
25 seconds before trying another position.
Synchronizing the rolling code
Pay attention to the "Important safety notes"
(Y page 226).
If the garage door system uses a rolling code,
you will also have to synchronize the garage
door system with the integrated garage door
opener in the rear-view mirror. To do this you will
need to use the programming button on the door
drive control panel. The programming button
may be located in different places depending on the manufacturer. It is usually located on the
door drive unit on the garage ceiling.
Familiarize yourself with the garage door drive
operating instructions, e.g. under "Program-
ming additional remote controls", before carry-
ing out the following steps.
Your vehicle must be within reach of the garage
door or gate opener drive. Make sure that nei-
ther your vehicle nor any persons/objects are
present within the sweep of the door or gate.
X Turn the SmartKey to position 2in the ignition
lock (Y page 109).
X Get out of the vehicle.
X Press the programming button on the door
drive unit.
Usually, you now have 30 second sto initiate
the next step. X
Get into the vehicle.
X Press previously programed button 0044,0087
or 0085 on the integrated garage door opener
repeatedly and in quick succession until the
door closes.
The rolling code synchronization is then com- plete.
Notes on programming the remote con-
trol
Canadian radio frequency laws require a "break"
(or interruption) of the transmission signals
after broadcasting for a few seconds. Therefore, these signals may not last long enough for the
integrated garage door opener. The signal is not
detected during programming. Comparable with Canadian law, some U.S. garage door openers
also feature a "break".
Proceed as follows:
R if you live in Canada
R if you have difficulties programming the
garage door opener (regardless of where you
live) as you follow the programming steps.
X Press and hold one of buttons 0044to0085 on the
integrated garage door opener.
After a short time, indicator lamp 0043lights up
yellow.
X Release the button.
Indicator lamp 0043flashes yellow.
X Press button 0084of garage door remote con-
trol 0083for two seconds, then release it for two
seconds.
X Press button 0084again for two seconds.
X Repeat this sequence on button 0084of remote
control 0083until indicator lamp 0043lights up
green.
When indicator lamp 0043lights up green: pro-
gramming is finished.
When indicator lamp 0043flashes green: pro-
gramming was successful. The next step is to
synchronize the rolling code.
X Release button 0084of remote control 0083of the
garage door drive.
If indicator lamp 0043lights up red: repeat the
programming process for the corresponding
button on the rear-view mirror. When doing
so, vary the distance between remote control 0083 and the rear-view mirror.
The required distance between remote con-
trol 0083and the integrated garage door opener
depends on the garage door drive system.
Several attempts might be necessary. You Features
227Stowage an d features Z

should test every position for at least
25 seconds before trying another position.
Problems when programming If you are experiencing problems programming
the integrated garage door opener on the rear-
view mirror, take note of the following instruc-
tions:
R Check the transmitter frequency used by
garage door drive remote control 0083and
whether it is supported. The transmitter fre-
quency can usually be found on the back of
remote control 0083for the garage door drive.
The integrated garage door opener is com-
patible with devices that have units which
operate in the frequency range of 280 to
433 MHz.
R Replace the batteries in garage door remote
control 0083. This increases the likelihood that
garage door remote control 0083will transmit a
strong and precise signal to the integrated
garage door opener.
R When programming, hold remote control 0083
at varying distances and angles from but-
tons 0044to0085 which you are programming. Try
various angles at a distance between 2and
8 inches (5to 20 cm) or at the same angle but at varying distances.
R If another remote control 0083is available for
the same garage door drive, repeat the same
programming steps with this remote control
0083. Before performing these steps, make sure
that new batteries have been installed in
garage door drive remote control 0083.
R Note that some remote controls only transmit
for a limited amount of time (the indicator
lamp on the remote control goes out). Press
button 0084on remote control 0083again before
transmission ends.
R Align the antenna cable of the garage door
opener unit. This can improve signal recep-
tion/transmission.
Opening/closing the garage door After it has been programmed, the integrated
garage door opener performs the function of the
garage door system remote control. Please also read the operating instructions for the garage
door system. X
Turn the SmartKey to position 2in the ignition
lock (Y page 109).
X Press button 0044,0087or0085 which you have
programmed to operate the garage door.
Garage door system with a fixed code: indi-
cator lamp 0043lights up green.
Garage door system with a rolling code: indi-
cator lamp 0043flashes green.
The transmitter will transmit a signal as long
as the button is pressed. The transmission is
halted after a maximum of ten seconds and
indicator lamp 0043lights up yellow.
X Press button 0044,0087or0085 again if necessary.
Clearing the memory Make sure that you clear the memory of the
integrated garage door opener before selling the vehicle.
X Turn the SmartKey to position 2in the ignition
lock (Y page 109).
X Press and hold buttons 0044and 0085.
The indicator lamp initially lights up yellow
and then green.
X Release buttons 0044and 0085.
The memory of the integrated garage door
opener in the rear-view mirror is cleared. Compass
Calling up the compass 0043
Rear-view mirror
0044 Compass display
0087 Opening
The compass displays in which compass direc-
tion the vehicle is currently traveling: N N,NE
NE, E
E,
SE
SE, S
S,SW
SW, W
Wor NW
NW. 228
FeaturesStowage and features

Engine compartment
Hood
Important safety notes G
WARNING
If the hood is unlatched, it may open up when the vehicle is in motion and block your view.
There is a risk of an accident.
Never unlatch the hood while driving. Before
every trip, ensure that the hood is locked. G
WARNING
When opening and closing the hood, it may
suddenly fall into the closed position. There is a risk of injury to persons within range of
movement of the hood.
Open and close the hood only when no one is
within its range of movement. 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.
If possible, let the drive system cool down and only touch the components described in the
following. G
WARNING
The engine compartment contains moving
components. Certain components, such as
the radiator fan, may continue to run or start
again suddenly when the ignition is off. There is a risk of injury.
If you need to do any work inside the engine
compartment:
R switch off the ignition
R never reach into the area where there is a
risk of danger from moving components,
such as the fan rotation area
R remove jewelry and watches
R keep items of clothing and hair, for exam-
ple, away from moving parts Opening the hood 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.
If possible, let the drive system cool down and only touch the components described in the
following. 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.
! Make sure that the windshield wipers are
not folded away from the windshield. You
could otherwise damage the windshield wip-
ers or the hood. X
Make sure that the windshield wipers are
switched off.
X Pull release lever 0043on the hood.
The hood is released. Engine compartment
231Maintenance and care Z

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

X
Clean sensors 0043of 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
Make sure that the vehicle is stationary and
that the SmartKey is in position 2in the igni-
tion lock.
X To clean the rear view camera: use clear
water and a soft cloth to clean camera
lens 0043. 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 dam-
age to the display.
X Before cleaning the display, make sure that it
is switched off and has cooled down.
X Clean the display surface using a commer-
cially available microfiber cloth and TFT/LCD
display cleaner.
X Dry the display surface using a dry microfiber
cloth.
Cleaning the plastic trim G
WARNING
Care products and cleaning agents containing solvents cause surfaces in the cockpit to
become porous. As a result, plastic parts may
come loose in the event of air bag deploy-
ment. There is a risk of injury.
Do not use any care products and cleaning
agents to clean the cockpit.
! Do not affix the following to plastic surfaces:
R stickers
R films
R scented oil bottles or similar items
You can otherwise damage the plastic.
! Do not allow cosmetics, insect repellent or
sunscreen to come into contact with the plas-
tic trim. This maintains the high-quality look of the surfaces.
X Wipe the plastic trim with a damp, lint-free
cloth, e.g. a microfiber cloth.
X Heavy soiling: use care and cleaning prod-
ucts recommended and approved by
Mercedes-Benz.
The surface may change color temporarily.
Wait until the surface is dry again. 238
CareMaintenance and care

Where will I find...?
Vehicle tool kit
General notes Vehicles with a TIREFIT kit: the TIREFIT kit is
located in the stowage well under the cargo
compartment floor.
Vehicles with a tire-change tool kit: the tire-
change tool kit is in the stowage well under the
cargo compartment floor.
Apart from certain country-specific variations,
the vehicles are not equipped with a tire-change tool kit. Some tools for changing a wheel are
specific to the vehicle. For more information on
which tire changing tools are required and
approved to perform a wheel change on your
vehicle, consult a qualified specialist workshop.
Tools required for changing a wheel may
include, for example:
R Jack
R Wheel chock
R Lug wrench
R Alignment bolt
Vehicles with a TIREFIT kit 0043
Tire inflation compressor
0044 Tire sealant filler bottle
0087 Towing eye
X Open the tailgate.
X Lift the cargo compartment floor upwards
(Y page 214).
X Use the TIREFIT kit (Y page 243) or remove it.
Towing eye 0087is located under tire inflation
compressor 0043. Vehicles with a tire-change tool kit X
Open the tailgate.
X Lift the cargo compartment floor upwards
(Y page 214).
X Remove the tire-change tool kit.
The tire-change tool kit contains:
R Jack
R Lug wrench
R One pair of gloves
R Folding wheel chock Flat tire
Preparing the vehicle
Your vehicle may be equipped with:
R MOExtended tires (tires with run-flat proper-
ties) (Y page 242)
Vehicle preparation is not necessary on vehi-
cles with MOExtended tires
R a TIREFIT kit (Y page 241)
Vehicles equipped with MOExtended tires are
not equipped with a TIREFIT kit at the factory. It
is therefore recommended that you additionally
equip your vehicle with a TIREFIT kit if you mount tires that do not feature run-flat properties, e.g.
winter tires. A TIREFIT kit may be obtained from a qualified specialist workshop.
Information on changing and mounting wheels
(Y page 275).
X Stop the vehicle on solid, non-slippery and
level ground, as far away as possible from
traffic.
X Switch on the hazard warning lamps.
X Secure the vehicle against rolling away
(Y page 128).
X If possible, bring the front wheels into the
straight-ahead position.
X Switch off the drive system.
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.
X Make sure that the passengers are not endan-
gered as they do so. Make sure that no one is
near the danger area while a wheel is being Flat tire
241Breakdown assistance

X
Remove filler hose 0084and connector 0087from
the bottom section of the tire inflation com-
pressor housing 0044.
X Slide the yellow filler hose connector into the
mounting on yellow cap 0083of tire sealant filler
bottle 0043until the connector engages.
X With the sealing rings in front, slide yellow cap
0083 of tire sealant bottle 0043into the mounting
of tire inflation compressor 0044.
Yellow cap 0083and both hooks must engage. X
Remove the cap from valve 006Bon the faulty
tire.
X Screw filler hose 006Conto valve 006B.
X Insert plug 0087into a 12 V socket in your vehi-
cle.
Observe the notes on sockets (Y page 218).
X Turn the SmartKey to position 1in the ignition
lock (Y page 109).
X Press on and off switch 0085on the tire inflation
compressor to ON.
The tire inflation compressor is switched on.
The tire is inflated.
First, tire sealant is pumped into the tire. The
pressure can briefly rise to approximately
500 kPa (5 bar/73 psi). Do not switch off the tire inflation com-
pressor during this phase.
X Let the tire inflation compressor run for a
maximum of ten minutes. The tire should then
have attained a pressure of at least 200 kPa
(2.0 bar/29 psi).
If a pressure of 200 kPa (2.0 bar/29 psi) has
been at tained after five minutes, see "Tire pres-
sure reached" (Y page 245).
If a tire pressure of 200 kPa (2.0 bar/29 psi) has not been attained after five minutes, see "Tire
pressure not reached" (Y page 244).
If tire sealant has escaped, clean it off affected
areas as quickly as possible. Use plain water if
possible.
If your clothes are soiled with tire sealant, have them cleaned with perchloroethylene at a dry
cleaner as soon as possible.
Tire pressure not reached If a tire pressure of 200 kPa (2.0 bar/29 psi) has
not been attained after ten minutes:
X Switch off the tire inflation compressor.
X Unscrew the filler hose from the valve of the
faulty tire.
Note that tire sealant may escape when you
unscrew the filler hose.
X Very slowly drive forwards or reverse approx-
imately 30 ft (10 m).
X Pump up the tire again.
After a maximum of ten minutes, the tire pres-
sure must be at least 200 kPa (2.0 bar/
29 psi). G
WARNING
If the required tire pressure is not reached
after the specified time, the tire is too badly
damaged. The tire sealant cannot repair the
tire in this instance. Damaged tires and a tire pressure that is too low can significantly
impair the vehicle's braking and driving char-
acteristics. There is a risk of accident.
Do not continue driving. Contact a qualified
specialist workshop. 244
Flat tireBreakdown assistance

Tire pressure reached
G
WARNING
A tire temporarily sealed with tire sealant
impairs the driving characteristics and is not
suitable for higher speeds. There is a risk of
accident.
You should therefore adapt your driving style
accordingly and drive carefully. Do not exceed the specified maximum speed with a tire that
has been repaired using tire sealant.
The maximum permissible speed for a tire
sealed with tire sealant is 50 mph (80 km/h).
The upper part of the TIREFIT sticker must be
affixed to the instrument cluster in the driver's
field of vision.
If a tire pressure of 200 kPa (2.0 bar/29 psi) has been attained after ten minutes:
X Switch off the tire inflation compressor.
X Unscrew the filler hose from the valve of the
faulty tire.
Note that tire sealant may escape when you
unscrew the filler hose.
X Stow the tire sealant bottle and the tire infla-
tion compressor.
X Pull away immediately.
X Stop after driving for approximately ten
minutes and check the tire pressure with the
tire inflation compressor.
The tire pressure must now be at least
130 kPa (1.3 bar/19 psi). G
WARNING
If the required tire pressure is not reached
after driving for a short period, the tire is too
badly damaged. The tire sealant cannot repair the tire in this instance. Damaged tires and a
tire pressure that is too low can significantly
impair the vehicle's braking and driving char-
acteristics. There is a risk of accident.
Do not continue driving. Contact a qualified
specialist workshop.
i In cases such as the one mentioned above,
contact an authorized Mercedes-Benz Cen-
ter. Or call 1-800-FOR-MERCedes (in the
USA) or 1-800-387-0100 (in Canada). X
Correct the tire pressure if it is still at least
130 kPa (1.3 bar/19 psi). See the Tire and
Loading Information placard on the driver's
side B-pillar or the tire pressure table in the
charge socket flap for values.
X To increase the tire pressure: switch on the
tire inflation compressor. X
To reduce the tire pressure: depress pres-
sure release button 0043next to pressure
gauge 0044.
X When the tire pressure is correct, unscrew the
filler hose from the valve of the sealed tire.
Note that tire sealant may escape when you
unscrew the filler hose.
X Screw the valve cap onto the tire valve of the
sealed tire. X
To remove the tire sealant bottle from the tire
inflation compressor, press together the lock- ing tabs on the yellow cap.
X Pull the tire sealant bottle out of the tire infla-
tion compressor.
The filler hose remains attached to the tire
sealant bottle. Flat tire
245Breakdown assistance Z