PEUGEOT 508 Handbook page 196

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.
194
Deactivation / Activation of the
front and rear parking sensors
With audio system or for HYbrid4 version
the function is deactivated by pressing this button. the indicator lamp in the button comes on.
Pressing this button again reactivates the function. the indicator lamp in the button goes off.
the function will be deactivated
automatically if a trailer is being towed
or a bicycle carrier is fitted (vehicle
fitted with a towbar or bicycle carrier
recommended by PeugeOt).
With touch screen