CITROEN Grand C4 PICASSO Owner's Handbook Manual page 192

Driving
Front parking sensors
In addition to the rear parking sensors, the front
parking sensors are triggered when an obstacle
is detected in front and the speed of the vehicle
is still below 6 mph (10 km/h).
The front parking sensors are interrupted if
the vehicle stops for more than three seconds
in forward gear, if no further obstacles are
detected or when the speed of the vehicle
exceeds 6 mph (10 km/h).
The sound emitted by the speaker (front
or rear) indicates whether the obstacle
is in front or behind.
190
Deactivation / Activation of the
front and rear parking sensors
The system is deactivated in the " Driving
assistance" menu in the touch screen tablet.
Press this button. The indicator
lamp in the button comes on.
Pressing this button again reactivates the system.
The indicator lamp in the button goes off.
The system will be deactivated
automatically if a trailer is being
towed or a bicycle carrier is fitted on
a towbar (vehicle fitted with a towbar
installed in line with the manufacturer's
recommendations).
The parking sensors are deactivated
while the Park Assist system is
measuring a space.
See the "Park Assist" section.
Operating fault
In the event of a malfunction of
the system, when reverse gear
is engaged this warning lamp is
displayed in the instrument panel and/
or a message appears, accompanied
by an audible signal (short beep).
Contact a CITROËN dealer or a qualified
workshop.
In bad weather or in winter, ensure
that the sensors are not covered with
mud, ice or snow. When reverse gear is
engaged, an audible signal (long beep)
indicates that the sensors may be dirty.
Certain sound sources (motorcycle,
lorry, pneumatic drill, etc.) may trigger
the audible signals of the parking
sensor system.
High pressure jet wash
When washing your vehicle, do not
direct the lance within 30 cm of the
sensors.