CITROËN DS4 Owner's Handbook Manual page 114

Triggering of the alarm
This is indicated by sounding of the siren and
flashing of the direction indicators for
thirty seconds.
The monitoring functions remain active until
the alarm has been triggered eleven times in
succession.
When the vehicle is unlocked using the
remote control, rapid flashing of the indicator
lamp in the button informs you that the alarm
was triggered during your absence. When
the ignition is switched on, this flashing stops
immediately.
Failure of the remote control
To deactivate the monitoring functions:
unlock the vehicle using the key in the
driver's door lock,
open the door; the alarm is triggered,
switch on the ignition; the alarm stops;
the indicator lamp in the button goes off.
Locking the vehicle without
activating the alarm
Lock or deadlock the vehicle using the key
in the driver's door lock.
Operating fault
When the ignition is switched on, fixed
illumination of the indicator lamp in the button
indicates a fault with the system.
Have it checked by a CITROËN dealer or a
qualified workshop.