CITROEN C-ZERO Handbook page 22

Access
Remote control problem
In the event of a fault with the remote control,
you can no longer unlock or lock your vehicle.
F First of all, use the key in the driver's door
lock to unlock or lock your vehicle.
F Secondly, ask a CITROËN dealer to check
the operation of the remote control and to
replace the battery if necessary.
20
Lost keys
See a CITROËN dealer with the vehicle
registration certificate and your ID.
A CITROËN dealer can retrieve the key
code and the transponder code to order the
replacement key.
Remote control
The high frequency remote control is a
sensitive system; do not operate it while it is
in your pocket as there is a possibility that
it may unlock the vehicle without you being
aware of it.
Do not repeatedly press the buttons of your
remote control when out of range and out of
sight of your vehicle, as it may stop working.
The remote control does not operate when
the key is in the ignition, even when the
ignition is switched off.
Locking the vehicle
Driving with the doors locked may make
access to the passenger compartment by
the emergency services more difficult in an
emergency.
As a safety precaution (with children on
board), remove the key from the ignition
when leaving the vehicle, even for a short
time.
https://www.automotive-manuals.net/
Anti-theft protection
Do not make any modifications to the electronic
vehicle immobiliser system; this could cause
malfunctions.
When purchasing a second-hand vehicle
Have the key codes memorised by a CITROËN
dealer, to ensure that the keys in your
possession are the only ones which can start
the vehicle.