Multi-Purpose Display and Instruments 143
In the event of faults, Tyre Pressure Monitoring
cannot monitor the tyre pressure. A distinction is
made between partial monitoring and inactive
system.
In the case of partial monitoring, the warning light
lights up on the instrument panel. No message is
output on the multi-purpose display.
If Tyre Pressure Monitoring is not active, the
warning light lights up on the instrument panel and
a corresponding message is output on the multi-
function display.
The warning light goes out as soon as all faults
have been remedied.
Tyre Pressure Monitoring switches to partial
monitoring if:
– there are up to two wheel transmitters not
present or faulty (e.g. a spare wheel or collaps-
ible spare wheel is fitted that does not have a
wheel transmitter).
In the event of partial monitoring, the value “_._” is
displayed in the sub-menu TYRE PRESSURE (filling
information) at the position of the faulty or missing
wheel transmitter.
Tyre Pressure Monitoring is not active in the
following cases:
– Tyre Pressure Monitoring is faulty,
– at least three wheel transmitters for Tyre
Pressure Monitoring are faulty or not present,
– temporarily after changing a wheel,
– too many wheel transmitters have been
detected,
– there is external interference by other radio
sources, e.g. wireless headphones,
– tyre temperatures are too high.
f For information on messages on the multi-
purpose display:
Please observe the chapter “OVERVIEW OF
WARNING MESSAGES” on Page 151.
Notes on tyre pressure
Pressure increase as the result of
temperature increase
In accordance with physical principles,
the tyre pressure changes as the temperature
changes. The tyre pressure increases or
decreases by around 0.1 bar (1.5 psi) for every
10 °C change in temperature.
Tyre pressure specifications
The tyre pressure must match the prescribed
value (required pressure).
You can find information on the tyre pressure for
cold tyres (20 °C):
– in the sub-menu TYRE PRESSURE (filling infor-
mation):
as a required pressure for each axle if Tyre
Pressure Monitoring has not yet been taught
the corresponding values,
– in the front left door aperture for each wheel,
– in the Technical Data chapter in this Driver’s
Manual: Please observe the chapter “TYRE
PRESSURES, COLD” on Page 367.
If Tyre Pressure Monitoring has been taught the
corresponding values, the deviations from the
required pressure are shown in the sub-menu
TYRE PRESSURE (filling information) independ-
ently of the tyre temperature. The correct tyre
pressure adjustment can be made for a wheel on
the basis of this display information even if the
tyres are warm.
Insufficient tyre filling pressure can cause tyres to
overheat when driving and thus be damaged –
even invisibly.
Hidden tyre damage is not eliminated by subse-
quently correcting the tyre pressure.
f For this reason, always make sure that the tyre
pressure is correct.
f For further information on maintenance and
care of tyres and wheels:
Please observe the chapter “TYRES AND
WHEELS” on Page 292.
Faults in Tyre Pressure Monitoring
English 
