warning light MERCEDES-BENZ A-CLASS HATCHBACK 2015 Owners Manual

does not permit any reliable conclusion about
the tyre pressure. On vehicles fitted with the
electronic tyre pressure monitor, the tyre
pressure can be checked using the on-board
computer.
If possible, only correct tyre pressures when
the tyres are cold.
The tyres are cold:
R if the vehicle has been parked with the tyres
out of direct sunlight for at least three
hours and
R if the vehicle has not been driven further
than 1.6 km
Depending on the ambient temperature, the
vehicle speed and the load on the tyres, the
tyre temperature and thus the tyre pressure
changes by approximately 10 kPa (0.1 bar/
1.5 psi) per 10 †. Take this into account
when checking the pressure of warm tyres.
Only correct the tyre pressure if it is too low
for the current operating conditions.
Driving with tyre pressure that is too high or
too low can:
R shorten the service life of the tyres
R cause increased tyre damage
R have a negative effect on handling charac-
teristics and thus driving safety (e.g. aqua- planing)
The tyre pressure values given for low loads
are minimum values which offer you good ride
comfort characteristics.
However, you can also use the values given
for higher loads. These are permissible and
will not adversely affect the running of the
vehicle. Tyre pressure loss warning system
General notes While the vehicle is in motion, the tyre pres-
sure loss warning system monitors the set
tyre pressure using the rotational speed of
the wheels. This enables the system to detect significant pressure loss in a tyre. If the speed of rotation of a wheel changes as a result of a
loss of pressure, a corresponding warning
message will appear in the multifunction dis-
play.
You can recognise the tyre pressure loss
warning by the Run Flat Indicator
Run Flat Indicator
active Restart with OK active Restart with OK message which
appears in the multifunction display in the
Serv.
Serv.menu. Information on the message dis-
play can be found in the "Restarting the tyre
pressure loss warning system" section
(Y page 364).
Important safety notes The tyre pressure warning system does not
warn you of an incorrectly set tyre pressure.
Observe the notes on the recommended tyre
pressure (Y page 362).
The tyre pressure loss warning does not
replace the need to regularly check the tyre
pressures. An even loss of pressure on sev-
eral tyres at the same time cannot be detec-
ted by the tyre pressure loss warning system.
The tyre pressure monitor is not able to warn
you of a sudden loss of pressure, e.g. if the
tyre is penetrated by a foreign object. In the
event of a sudden loss of pressure, bring the
vehicle to a halt by braking carefully. Avoid
abrupt steering manoeuvres.
The function of the tyre pressure loss warning system is limited or delayed if:
R snow chains are fitted to your vehicle's
tyres.
R road conditions are wintry.
R you are driving on sand or gravel.
R you adopt a very sporty driving style (cor-
nering at high speeds or driving with high
rates of acceleration).
R you are towing a very heavy or large trailer.
R you are driving with a heavy load (in the
vehicle or on the roof). Tyre pressure
363Wheels and tyres Z

If there is a substantial loss of pressure, the
warning threshold for the warning message is aligned to the reference values taught-in.
Restart the tyre pressure monitor after
adjusting to the cold tyre pressure
(Y page 366). The current pressures are
saved as new reference values. This will
ensure that a warning message will only
appear if the tyre pressure drops significantly.
The tyre pressure monitor does not warn you of an incorrectly set tyre pressure. Observe
the notes on the recommended tyre pressure
(Y page 362).
The tyre pressure monitor is not able to warn you of a sudden loss of pressure, e.g. if the
tyre is penetrated by a foreign object. In the
event of a sudden loss of pressure, bring the
vehicle to a halt by braking carefully. Avoid
abrupt steering manoeuvres.
The tyre pressure monitor has a yellow warn-
ing lamp in the instrument cluster for indicat-
ing a pressure loss or malfunction. Depending on how the warning lamp flashes or lights up,
a tyre pressure that is too low or a malfunc-
tion in the tyre pressure monitor is indicated:
R if the warning lamp is lit continuously, the
tyre pressure on one or more tyres is sig-
nificantly too low. The tyre pressure moni-
tor is not malfunctioning.
R if the warning lamp flashes for around a
minute and then remains lit constantly, the
tyre pressure monitor is malfunctioning.
In addition to the warning lamp, a message
appears in the multifunction display. Observe
the information on display messages
(Y page 283).
It may take up to ten minutes for a malfunc-
tion of the tyre pressure monitor to be indi-
cated. A malfunction will be indicated by the
tyre pressure warning lamp flashing for
approximately one minute and then remain-
ing lit. When the fault has been rectified, the
tyre pressure warning lamp goes out after you
have driven for a few minutes.
The tyre pressure values indicated by the on- board computer may differ from those meas- ured at a filling station using a pressure
gauge. The tyre pressures shown by the on-
board computer refer to those measured at
sea level. At high altitudes, the tyre pressure
values indicated by a pressure gauge are
higher than those shown by the on-board
computer. In this case, do not reduce the tyre
pressures.
The operation of the tyre pressure monitor
can be affected by interference from radio
transmitting equipment (e.g. radio head-
phones, two-way radios) that may be being
operated in or near the vehicle.
Checking the tyre pressure electroni-
cally X
Make sure that the key is in position 2in the
ignition lock (Y page 157).
X Press =or; on the steering wheel
to select the Serv.
Serv.menu.
X Press the 9or: button to select
Tyre pressure Tyre pressure.
X Press the abutton.
The current tyre pressure for each wheel
will be displayed in the multifunction dis-
play.
If the vehicle was parked for longer than
20 minutes, the Tyre Tyrepressures
pressures will
willbe
be
displayed after a few minutes of
displayed after a few minutes of
driving driving message is shown.
After a teach-in period, the tyre pressure
monitor automatically detects new wheels or
new sensors. As long as a clear allocation of
the tyre pressure values to the individual
wheels is not possible, the Tyre pressure Tyre pressure
monitor active
monitor active message is shown instead
of the tyre pressure display. The tyre pres-
sures are already being monitored.
If an emergency spare wheel is fitted, for a
few minutes the system may continue to
show the tyre pressure of the wheel that has been removed. If this occurs, note that the
value displayed for the position where the
spare wheel is fitted is not the same as the
current tyre pressure of the emergency spare wheel. Tyre pressure
365Wheels and tyres Z

Warning messages of the tyre pressure
monitor If the tyre pressure monitor detects a pres-
sure loss in one or more tyres, a warning mes-
sage is shown in the multifunction display.
The yellow tyre pressure warning lamp then
lights up.
R If the Please correct tyre pressure
Please correct tyre pressure
message appears in the multifunction dis-
play, the tyre pressure in at least one tyre is too low. The tyre pressure must be correc-ted when the opportunity arises.
R If the Tyre pressure Check tyre(s)
Tyre pressure Check tyre(s)
message appears in the multifunction dis-
play, the tyre pressure in one or more tyres has dropped significantly. The tyres must
be checked.
R If the Tyre pressure Caution Tyre
Tyre pressure Caution Tyre
malfunction malfunction message appears in the mul-
tifunction display, the tyre pressure in one
or more tyres has dropped suddenly. The
tyres must be checked.
Observe the instructions and safety notes in
the display messages in the "Tyres" section
(Y page 283).
If the wheel positions on the vehicle are inter-
changed, the tyre pressures may be displayed for the wrong positions for a short time. After
a few minutes of driving, this is rectified and
the tyre pressures are displayed for the cor-
rect positions.
Restarting the tyre pressure monitor When you restart the tyre pressure monitor,
all existing warning messages are deleted and
the warning lamps go out. The monitor uses
the currently set tyre pressures as the refer-
ence values for monitoring. In most cases, the
tyre pressure monitor will automatically
detect the new reference values after you
have changed the tyre pressure. However,
you can also set reference values manually as described here. The tyre pressure monitor
then monitors the new tyre pressure values. X
Use the table on the inside of the fuel filler
flap to ensure that the tyre pressure is set
correctly in all four tyres for the current
operating conditions.
Also observe the notes in the section on
tyre pressures (Y page 362).
X Make sure that the key is in position 2in the
ignition lock (Y page 157).
X Press =or; on the steering wheel
to select the Serv.
Serv.menu.
X Press the 9or: button to select
Tyre pressure
Tyre pressure.
X Press the abutton.
The multifunction display shows the cur-
rent tyre pressure for each tyre or the
Tyre pressures will be displayed Tyre pressures will be displayed
after after a
afew
few minutes
minutes of
ofdriving
driving mes-
sage.
X Press the :button.
The multifunction display shows the Use
Use
current current pressures pressures as
asnew
new reference
reference
values
values message.
If you wish to confirm the restart: X Press the abutton.
The Tyre press. monitor restarted
Tyre press. monitor restarted
message appears in the multifunction dis-
play.
After you have driven for a few minutes, the
system checks whether the current tyre
pressures are within the specified range.
The new tyre pressures are then accepted
as reference values and monitored.
If you wish to cancel the restart:
X Press the %button.
The tyre pressure values stored at the last
restart will continue to be monitored. 366
Tyre pressureWheels and tyres