Page 216 of 267
214Vehicle carePush the screwdriver through therecess in the adapter. Remove the
cover by pulling the screwdriver.No.Circuit1–2Climate control system, fan3Power seat driver side4Cigarette lighter/Power outlet
front5–6Power window front7ABS8Heated steering wheel9Body control module10Power window rear11Sunroof12Body control module13Seat heating (only on vehicles
without alarm horn)14Exterior mirror/Rain sensor/
Lane keep assist/High beam
assist15Body control moduleNo.Circuit16Body control module17Body control module18Body control module19Data link connector20Airbag system21Climate control system22Central locking system, tailgate23Electronic key system24Power seat memory function25Illumination switch steering
wheel26Ignition switch/Steering column
lock27Body control module28USB socket29–30Selector lever31Rear window wiper
Page 221 of 267

Vehicle care219The driver is responsible for correct
adjustment of tyre pressure.9 Warning
If the pressure is too low, this can
result in considerable tyre warm-
up and internal damage, leading to tread separation and even to tyre
blow-out at high speeds.
If the tyre pressure must be reduced
or increased on a vehicle with tyre
pressure monitoring system, switch
off ignition.
Temperature dependencyThe tyre pressure depends on thetemperature of the tyre. During
driving, tyre temperature and
pressure increase. Tyre pressure
values provided on the tyre
information label and tyre pressure
chart are valid for cold tyres, which
means at 20 °C.
The pressure increases by nearly
1.5 psi for a 10 °C temperature
increase. This must be considered
when warm tyres are checked.
The tyre pressure value displayed in
the Driver Information Centre shows
the real tyre pressure. A cooled down
tyre will show a decreased value,
which does not indicate an air leak.
Tyre pressure monitoringsystem
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.
Notice
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.
Midlevel display:
Select the Tyre pressure page under
the Vehicle Information Menu ? in
the Driver Information Centre 3 97.
Uplevel display:
Page 222 of 267

220Vehicle care
Select the Tyre pressure page under
the Info Menu in the Driver
Information Centre 3 97.
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.
Temperature dependency 3 218.
A detected low tyre pressure
condition is indicated by the control
indicator w 3 95.
If w illuminates, stop as soon as
possible and inflate the tyres as
recommended 3 253.
If w flashes for 60-90 seconds 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.
If w illuminates at lower temperatures
and extinguishes after driving, this
could be an indicator for approaching a low tyre pressure condition. Check
tyre pressure.
Vehicle messages 3 104.
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 spare wheel or temporary spare
wheel is not equipped with pressure
sensors. The tyre pressure
monitoring system is not operational
for these tyres. Control indicator w
illuminates. For the further three
tyres, 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 the
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 3 253, and
select the appropriate setting in the
Page 223 of 267

Vehicle care221Tyre load menu in the Driver
Information Centre 3 97. This setting
is the reference for the tyre pressure
warnings.
The Tyre load menu only appears if
the vehicle is in a standstill and the
parking brake is applied. On vehicles
with automatic transmission the
selector lever has to be in P.
Midlevel display:
Select the Tyre load page under the
Vehicle Information Menu ? in the
Driver Information Centre 3 97.
Select
● Light for comfort pressure up to
three people.
● Eco for Eco pressure up to three
people.
● Max for full loading.
Uplevel display:
Select the Tyre load page under the
Options Menu in the Driver
Information Centre 3 97.
Select
● Light for comfort pressure up to
three people.
● Eco for Eco pressure up to
three people.
● Max for full loading.
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 the 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 go
off 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
Page 224 of 267

222Vehicle carewheel and left side rear wheel. Theturn signal light at the current active
position is illuminated until sensor is
matched.
Consult a workshop for service or purchase a relearn tool. 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. Midlevel display: Use MENU on the turn signal
lever to select the Vehicle
Information Menu ? in the
Driver Information Centre.
Uplevel display:Press p on the steering wheel to
open main menu page.
Select the Info page with Q or P.
Confirm with 9.
5. Select the tyre pressure menu. Midlevel display:
Uplevel display:
6. Midlevel display: Press SET/CLR to begin the
sensor matching process. A
message requesting acceptance
of the process should be
displayed.
Press SET/CLR again to confirm
the selection. The horn sounds
twice to indicate that the receiver
is in relearn mode.
Uplevel display:
Press 9 to begin the sensor
matching process. The horn
sounds twice to indicate that the receiver is in relearn mode.
7. Start with the left side front wheel.
Page 225 of 267

Vehicle care2238. Place the relearn tool against thetyre 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.
9. Proceed to the right side front wheel, and repeat the procedure
in Step 8.
10. Proceed to the right side rear wheel, and repeat the procedure
in Step 8.
11. Proceed to the left side rear wheel, and repeat the procedure
in Step 8. The horn sounds twice
to indicate that the sensor
identification code has been
matched to the left side rear
wheel, and the tyre pressure
sensor matching process is no
longer active.
12. Turn off the ignition.13. Set all four tyres to the recommended air pressure level
as indicated on the tyre pressure
information label.
14. Ensure the tyre loading status is set according to the selected
pressure 3 97.
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 minimumtread 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 six years.