CITROËN DS5 Owner's Handbook Manual page 192

Deactivation
Only the passenger's front airbag can be
deactivated:
 insert the key in the passenger airbag
deactivation switch,
 turn it to the "OFF" position,
 then, remove the key keeping the switch in
the new position.
According to version, this warning
lamp comes on either in the
instrument panel or in the seat belt
and passenger's front airbag warning lamp
display when the ignition is on and until the
airbag is reactivated.
To assure the safety of your child,
the passenger's front airbag must
be deactivated when you install a
"rear facing" child seat on the front
passenger seat.
Otherwise, the child would risk being
seriously injured or killed if the airbag
were deployed.
Reactivation
When you remove the child seat, with
the ignition off , turn the switch to the
"ON" position to reactivate the airbag and so
assure the safety of your front passenger in the
event of an impact.
With the ignition on, this warning
lamp comes on in the seat belt and
passenger's front airbag warning lamp
display for approximately one minute, if
the passenger's front airbag is activated.
Operating fault
If this warning lamp comes on in the
instrument panel, accompanied by an
audible warning and a message in the
instrument panel screen, contact a
CITROËN dealer or a qualified workshop to have
the system checked. The airbags may no longer
be deployed in the event of a serious impact.