CITROEN DS3 Owner's Handbook Manual page 114

Automatic operation of
hazard warning lamps
When braking in an emergency, depending on
the deceleration, the hazard warning lamps
come on automatically.
They switch off automatically the first time you
accelerate.
You can also switch them off by pressing
the button.
Horn
Audible warning to alert other road users to an
imminent danger.
Press one of the spokes of the steering
wheel.
Use the horn moderately and only in
the following cases:
- immediate danger,
- overtaking a cyclist or pedestrian,
- when approaching an area where
there is no visibility.
Safety