One year later, Porsche introduced its Cayenne, a new model and a new direction. While engineering the large, five-passenger SUV, Porsche reconsidered some aspects of its passive-restraint system. While the Cayenne’s basic system layout remained the same, its front airbags offered two stages of deployment based on impact severity. Impact sensors in the control unit distinguish between lower- and higher-force decelerations. Two impact sensors were added near the front bumper for earlier and more precise determinations of crash scenarios, including more complex offset frontal impacts to offer improved airbag deployment options. The airbags are fitted with two-stage gas generators to allow them to deploy less aggressively if possible.
The Cayenne also offered a new side-collision system made up of 10-liter, seat-integrated thorax airbags and 30-liter side-curtain airbags built into the roof frame, all using acid-free gas generators. The system has four side-impact sensors, two at the B-pillars and two at the rear wheel housings. The Cayenne carried the pyrotechnic seatbelt tensioner first seen in the 2002 986s and 996s.
For 2005, the 911 and Boxster were new. Both cars, known internally as the 997 and 987, got two additional impact sensors near the headlights to detect the point and direction of an impact. The system retained impact sensors in the control unit and on each side of the car in the doorsills. The 997 was fitted with the two-stage front airbag system from the Cayenne, but the 987 retained a single-stage deployment system.
Due to the risk of serious or fatal injuries from a front airbag when a child seat is in use, Porsche made a dealer-installed key switch available to disable passenger-side front airbags in 997s and 987s. Since the airbag must be switched back on manually to protect a full-size passenger, a “Passenger Airbag Off” warning light illuminates on the center console — a message that is also displayed by the on-board computer.
The 997 and 987 featured a new generation of POSIP, with two airbags per side instead of one. An eight-liter thorax airbag was integrated into both front seats and a separate, eight-liter curtain-type head airbag deployed upward from the upper door trim panel, making the system suitable for use in both coupes and convertibles, a world first. 997s and 987s still featured the seatbelts with pyrotechnic belt tensioners as used in later 996s, but the height of the shoulder strap was made adjustable at the B-pillar to ensure proper seatbelt fit.
Airbag System Aging
The airbag systems in 944 Turbos are now more than 20 years old, while most airbag-equipped 928S4/GTs and 964s are roughly that old. So what about continued functionality and component integrity? The good news is that Porsche’s airbag systems are well engineered and supported by a sophisticated self-diagnostic capability. Even the early systems will detect minor changes within the system and return a fault code if specific electronic values are exceeded or operational issues detected.
Longterm exposure to high levels of moisture or corrosive conditions can be detrimental to components including wiring connections, but the system should recognize a change in resistance within the wiring and return a fault code. We’ve never seen documentation from Porsche stating that any airbag system component, including the airbags, must be replaced at a specific time interval to ensure operation.