From The Inside - PEUGEOT 208 Handbook

Access

From the inside

Locking
F Press the button.
This allows the doors and the boot to be locked.
The indicator lamp in the button comes on.
If one of the doors is open, locking of
the doors from the inside does not take
place.
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Unlocking
F Press the button again.
The indicator lamp in the button goes off.
When locking / deadlocking from
outside
When the vehicle is locked or
deadlocked from outside, the switch
does not operate.
F After normal locking, pull the
interior door lever to unlock the
vehicle.
F After deadlocking, you have to use
the remote control or the key to
unlock the vehicle.
Automatic central locking
The doors can lock automatically while driving
(speed above 6 mph [10 km/h]).
To turn this function on or off (on by default).
F press and hold the button until
there is an audible signal and/or
a message in the screen.
Driving with the doors locked may make
access to the passenger compartment
by the emergency services more
difficult in an emergency.