Ford Focus Owner's Manual page 107

seat is empty, and the safety belt is not properly buckled, the front
passenger seat side airbag will be turned off by the front passenger
sensing system. The airbag was designed to inflate between the door
panel and occupant to further enhance the protection provided
occupants in side impact collisions.
The airbag SRS is designed to activate when the vehicle sustains lateral
deceleration sufficient to cause the sensors to close an electrical circuit
that initiates airbag inflation.
The fact that the airbags did not inflate in a collision does not mean that
something is wrong with the system. Rather, it means the forces were
not of the type sufficient to cause activation. Side airbags are designed
to inflate in side-impact collisions, not roll-over, rear-impact, frontal or
near-frontal collisions, unless the collision causes sufficient lateral
deceleration.
Several air bag system components get hot after inflation. Do not
touch them after inflation.
If the side airbag has
deployed, the airbag will
not function again. The side
airbag system (including the
seat) must be inspected and
serviced by an authorized
dealer. If the airbag is not
replaced, the unrepaired area will
increase the risk of injury in a
collision.
Side curtain airbag system
2008 Focus (foc)
Owners Guide (post-2002-fmt)
USA (fus)
Seating and Safety Restraints
107