CITROËN DS4 Owner's Handbook Manual page 176

Tyre under-infl ation detection
System which automatically and continuously
checks the pressure of the tyres while driving.
Sensors fitted in each valve trigger a warning
in the event of problem (speed above 12 mph
(20 km/h)).
The tyre under-inflation detection
system is an aid to driving which does
not replace the need for the driver to be
vigilant or to drive responsibly.
Under-infl ated tyre
This warning lamp is displayed on the
instrument panel and/or a message appears
in the screen, accompanied by an audible
signal, to identify the wheel concerned.
Check the tyre pressures as soon as possible.
This check must be carried out when the tyres
are cold.
Puncture
The STOP warning lamp comes on
and/or this warning lamp is displayed on
the instrument panel, accompanied by
an audible signal and a message in the
screen identifying the wheel concerned.
Stop as soon as it is safe to do so, avoiding
any sudden movement of the steering
wheel and the brakes.
Repair or change the damaged wheel
(punctured or very deflated tyre), and have
the tyre pressure checked as soon as
possible.