BMW X1 Owner's Handbook Manual page 115

▷ Check the tyre pressure and adjust as nec‐
essary.
▷ Reset the system after a wheel change.
System limits
The system is not working correctly if no reset
has been run, for example, a flat tyre is repor‐
ted in spite of the correct tyre inflation pres‐
sure.
Tyre inflation pressure depends on the tem‐
perature of the tyre. By increasing tyre temper‐
ature, for example, when driving or with solar
radiation, the tyre inflation pressure increases.
Tyre inflation pressure decreases if the tyre
temperature drops. Through this behaviour, a
warning may be triggered if there are major
temperature drops, due to the given warning
limits.
No warning can be given by the system of ex‐
treme, sudden tyre failure caused by external
factors.
Malfunction
The yellow warning lamp flashes and is
then illuminated continuously. A Check
Control message is shown. No flat
tyres or loss of tyre pressure can be detected.
This may indicate one of the following:
▷ Wheel without TPM electronics is fitted:
have the vehicle checked by a Service
Partner or a qualified specialist workshop if
necessary.
▷ Malfunction: have the system checked by a
Service Partner or a qualified specialist
workshop.
▷ TPM has not completed a reset. Run a re‐
set of the system again.
▷ Fault due to systems or devices with the
same frequency: the system is automati‐
cally reactivated upon leaving the field of
interference.
Online Edition for Part no. 01 40 2 964 279 - VI/15
Security
Runflat indicator RPA
Principle
The system identifies a loss of tyre pressure
by comparing the speeds of rotation of the in‐
dividual wheels while the vehicle is in motion.
If a tyre loses pressure, its diameter changes.
This in turn alters the rotational speed of the
corresponding wheel. This is detected and re‐
ported as a flat tyre.
The system does not measure the tyre pres‐
sures as such.
Operating requirements
The system must have been initialised with
correct tyre inflation pressure, otherwise relia‐
ble signalling of a flat tyre cannot be assured.
Each time the tyre pressure is adjusted or a
tyre or wheel is changed, initialise the system
again.
Status display
The current status of the runflat indicator can
be shown on the Control Display, for example
whether the RPA is active.
1. "Vehicle information"
2. "Vehicle status"
3. "Flat Tyre Monitor (RPA)"
The status is displayed.
Initialising
On initialisation, the current tyre pressures are
saved as a reference for detection of a flat tyre.
The initialisation is started by confirming the
correct tyre inflation pressures.
When driving with snow chains fitted, do not
initialise the system.
On the Control Display:
1. "Vehicle information"
2. "Vehicle status"
3. "Perform reset"
Controls
115