Aston Martin DB 9 2010 Manual page 82

Accordingly, when the low tire pressure telltale comes ON, you
should stop and check your tires as soon as possible, and inflate them
to the proper pressure.
Driving on a significantly under-inflated tire causes the tire to
overheat and can lead to tire failure. Under-inflation also reduces fuel
efficiency and tire tread life, and may affect the vehicle's handling and
stopping ability.
Please note that the TPMS is not a substitute for proper tire
maintenance, and it is the driver's responsibility to maintain correct
tire pressures, even if under-inflation has not reached the level to set
the TPMS low tire pressure warning symbol to ON.
Your vehicle has also been equipped with a TPMS malfunction
telltale to show when the system is not operating properly.
4.20
The TPMS malfunction telltale is
combined with the low tire
pressure telltale (A).
When the system detects a
malfunction, the warning symbol
will flash for approximately one
minute and then stay ON. This
sequence will continue upon
subsequent vehicle start-ups as
long as the malfunction exists.
When the malfunction warning
symbol is ON, the system may
not be able to detect or signal low
tire pressure as intended.
TPMS malfunctions may occur for a variety of reasons, including the
installation of replacement or alternate tires or wheels on the vehicle
that prevent the TPMS from functioning properly.
Always check the TPMS malfunction telltale after replacing one or
more tires or wheels on your vehicle to make sure that the
replacement or alternate tires and wheels allow the TPMS to
continue to function properly.
Operation
The system consists of a control unit
(B), mounted in the front passenger
footwell, and tire pressure sensors,
one located in each road wheel.
Each pressure sensor constantly
monitors its tire pressure and sends
this information to the control unit.
B