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234Vehicle care
Remove the cover.
If equipped with tyre repair kit,
remove the complete box.
Fuse assignmentsNo.Circuit1–2Trailer outlet3Parking assist4Selective catalytic reduction
system5–6–7Power seat8–9Selective catalytic reduction
system10Nitrogen oxide sensor11Trailer module/Trailer socket12Trailer module13Trailer outlet14–15–
Page 240 of 289

238Vehicle careTyre pressure monitoring
system
The tyre pressure monitoring system
checks the pressure of all four tyres
once a minute when vehicle speed
exceeds a certain limit.Caution
Tyre pressure monitoring system
warns only about low tyre pressure condition and does not replace
regular tyre maintenance by the
driver.
All wheels must be equipped with pressure sensors and the tyres must
have the prescribed pressure.
Note
In countries where the tyre pressure
monitoring system is legally
required, the use of wheels without
pressure sensors will invalidate the
vehicle type approval.
The current tyre pressures can be
shown in the Driver Information
Centre.
Select the menu by the buttons on the turn signal lever.
Select Tyre pressure page under
Vehicle Information Menu ? 3 117.
System status and pressure warnings
are displayed by a message
indicating the corresponding tyre in
the Driver Information Centre.
The system considers the tyre
temperature for the warnings.
A detected low tyre pressure
condition is indicated by control
indicator w 3 115.
If w illuminates, stop as soon as
possible and inflate the tyres as
recommended 3 273.
If w flashes for 60-90 seconds and
then illuminates continuously, there is
a fault in the system. Consult a
workshop.
After inflating, some driving may be
required to update the tyre pressure
values in the Driver Information
Centre. During this time w may
illuminate.
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Vehicle care239If w illuminates at lower temperatures
and extinguishes after some driving,
this could be an indicator for
approaching a low tyre pressure
condition. Check tyre pressure.
Vehicle messages 3 123.
If the tyre pressure must be reduced
or increased, switch off ignition.
Only mount wheels with pressure
sensors, otherwise the tyre pressure
will not be displayed and w
illuminates continuously.
A temporary spare wheel is not
equipped with pressure sensors. The
tyre pressure monitoring system is
not operational for these wheels.
Control indicator w illuminates. For
the further three wheels the system remains operational.
The use of commercially available
liquid tyre repair kits can impair the
function of the system. Factory-
approved repair kits can be used.
Operating electronic devices or being
close to facilities using similar wave
frequencies could disrupt the tyre
pressure monitoring system.Each time the tyres are replaced, tyre pressure monitoring system sensors
must be dismounted and serviced.
For the screwed sensor: replace
valve core and sealing ring. For
clipped sensor: replace complete
valve stem.
Vehicle loading status
Adjust tyre pressure to load condition according to the tyre information label
or tyre pressure chart 3 273, and
select the appropriate setting in the Tyre load menu in the Driver
Information Centre 3 117. This
setting is the reference for the tyre
pressure warnings.
The Tyre load menu only appears if
the vehicle is at a standstill and the
parking brake is applied. On vehicles
with automatic transmission the
selector lever has to be in P.
Select Tyre load page under Vehicle
Information Menu ? in the Driver
Information Centre 3 117.
Select: ● Light for comfort pressure up to
3 people.
● Eco for Eco pressure up to
3 people.
● Max for full load.
Tyre pressure sensor matching
process
Each tyre pressure sensor has a
unique identification code. The
identification code must be matched
to a new wheel position after rotating
Page 242 of 289

240Vehicle carethe wheels or exchanging the
complete wheel set and if one or more tyre pressure sensors were replaced.The tyre pressure sensor matching
process should also be performed
after replacing a spare wheel with a
road wheel containing the tyre
pressure sensor.
The malfunction light w and the
warning message or code should extinguish at the next ignition cycle.The sensors are matched to the
wheel positions, using a relearn tool,
in the following order: left side front
wheel, right side front wheel, right
side rear wheel and left side rear
wheel. The turn signal light at the
current active position is illuminated
until sensor is matched.
Consult your workshop for service.
There are two minutes to match the
first wheel position, and five minutes
overall to match all four wheel
positions. If it takes longer, the
matching process stops and must be
restarted.
The tyre pressure sensor matching
process is:
1. Apply the parking brake.2. Turn the ignition on.
3. On vehicles with automatic transmission: set the selector
lever to P.
On vehicles with manual
transmission: select neutral.
4. Press MENU on the turn signal
lever to select the Vehicle
Information Menu ? in the
Driver Information Centre.
5. Turn the adjuster wheel to scroll to
the tyre pressure menu.6. Press SET/CLR to begin the
sensor matching process. A
message requesting acceptance
of the process should be
displayed.
7. Press SET/CLR again to confirm
the selection. The horn sounds
twice to indicate the receiver is in
relearn mode.
8. Start with the left side front wheel.
9. Place the relearn tool against the tyre sidewall, near the valve stem.Then press the button to activate
the tyre pressure sensor. A horn
chirp confirms that the sensor
identification code has been
matched to this wheel position.
10. Proceed to the right side front wheel, and repeat the procedure
in Step 9.
11. Proceed to the right side rear wheel, and repeat the procedure
in Step 9.
12. Proceed to the left side rear wheel, and repeat the procedure
in Step 9. The horn sounds twice
to indicate the sensor
identification code has been
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Vehicle care241matched to the left side rear tyre,
and the tyre pressure sensor
matching process is no longer
active.
13. Turn off the ignition.
14. Set all four tyres to the recommended air pressure level
as indicated on the tyre pressure
information label.
15. Ensure the tyre loading status is set according to the selected
pressure 3 117.
Tread depth
Check tread depth at regular
intervals.
Tyres should be replaced for safety
reasons at a tread depth of 2-3 mm
(4 mm for winter tyres).
For safety reasons, it is
recommended that the tread depth of
the tyres on one axle should not vary
by more than 2 mm.
The legally permissible minimum
tread depth (1.6 mm) has been
reached when the tread has worn
down as far as one of the tread wear
indicators (TWI). Their position is
indicated by markings on the
sidewall.
If there is more wear at the front than
the rear, swap round front wheels and rear wheels periodically. Ensure that
the direction of rotation of the wheels
remains the same.
Tyres age, even if they are not used.
We recommend tyre replacement
every 6 years.
Changing tyre and wheel
size
If tyres of a different size than thosefitted at the factory are used, it may be necessary to reprogramme the
speedometer as well as the nominal
tyre pressure and make other vehicle
modifications.
After converting to a different tyre
size, have the label with tyre
pressures replaced.9 Warning
Use of unsuitable tyres or wheels
may lead to accidents and will
invalidate the vehicle type
approval.
Wheel covers
Wheel covers and tyres that are
factory approved for the respective
vehicle and comply with all of the
relevant wheel and tyre combination requirements must be used.
If the wheel covers and tyres used are
not factory approved, the tyres must
not have a rim protection ridge.