CITROEN C4 Handbook page 136

Driving
– Towing a trailer (particularly a trailer without its
own braking system).
– Carrying long objects on roof bars.
– Driving with snow chains.
– Using an automatic car wash.
– Performing any maintenance (e.g. changing a
wheel, working inside the engine compartment).
– Placing the vehicle on a rolling bench in a
workshop.
– Towing the vehicle.
– Following a damage of the windscreen close
to the detection camera.
The system is automatically deactivated
when the use of certain types of
"space-saver" spare wheel (smaller diameter)
is detected, or if a fault with the brake pedal
switch or at least two brake lamps is detected.
Following a severe crash (e.g. with airbag
deployment), the system is automatically
deactivated.
Have it checked by a CITROËN dealer or a
qualified workshop.
In case the detection is degraded or
temporarily unavailable by environment
conditions, then a driver indication is not
displayed (because a driver action is not
requested).
It can be dangerous to drive if the brake
lamps are not in perfect working order.
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The driver must not overload the vehicle
(keep within the GVW limit and load
height limits for roof bars).
Collision Risk Alert
This function warns the driver if there is a risk
of collision with the preceding vehicle, or with a
pedestrian or cyclist.
Modifying the alert trigger threshold
The trigger threshold determines the sensitivity
with which the function warns of the risk of
collision.
The selected threshold is memorised when the
ignition is switched off.
With Touch screen BLUETOOTH audio
system or MyCitroën Play
The threshold is set via the Driving touch
screen menu.
► Select one of the three pre-defined
thresholds: "Far", "Normal" or "Close".
With MyCitroën Drive
The threshold is set via the Vehicle touch
screen menu.
► Select one of the three pre-defined
thresholds: "Far", "Normal" or "Close".
With MyCitroën Drive Plus
The threshold is set via the ADAS touch
screen application.
► Select one of the 3 preset thresholds: "Far",
"Medium" or "Near".
Operation
Depending on the collision risk detected by the
system and the alert trigger threshold chosen
by the driver, different levels of alert may be
triggered and displayed on the instrument panel.
The system takes into account the vehicle
dynamics, the difference speed of the own
vehicle and the object identified for the
collision risk, and the operation of the vehicle
(e.g. actions on the pedals, steering wheel) to
trigger the alert at the most relevant moment.
(orange)
Level 1: visual alert only, warning that the
preceding vehicle is very close.
The message "Vehicle close" is displayed.
(red)
Level 2: visual and audible alert, warning
that a collision is imminent.
The message "Brake!" is displayed.
Level 3: a micro-braking may be given,
confirming the risk of collision (optional).
While approaching a vehicle too quickly,
the level 2 alert may be displayed
directly.
Important: the level 1 alert depends on the
trigger threshold selected. It reacts only on
moving vehicles. It is disabled automatically
at lower speed.