One problem related to front air bag has been reported for the 2009 Subaru Impreza Sti. The most recently reported issues are listed below.
Passenger air bag does not turn on when passenger sits on it. The passenger weighs 105 pounds but if someone from 120 pounds and up it turns on. The 105 pound passenger has to bounce up and down to get the air bag to turn on sometimes it works and sometimes it doesn't.