Two problems related to air bag on-off switch have been reported for the 2008 Subaru Impreza. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Subaru Impreza based on all problems reported for the 2008 Impreza.
Immediately after purchasing a new 08 Subaru Impreza, I noticed that the passenger airbag on/off warning light will intermittently switch back and forth from on to off when a person 5'11' and 160 lb was sitting on the passenger seat. I went to the dealer and they recalibrated the cushion seat weight sensor. This did not solve the problem. I went back and, according to the dealer, following Subaru's instructions, they replaced the seat cushion (including all the sensors in it). This again did not solve the problem. The dealer maintenance manager told me that the weight sensors are very sensitive and all the Imprezas exhibit this (don't know why they would replace the seat cushion if they all exhibit this). I requested to meet the regional service manager, which has not happened yet. This is a severe safety failure with potential catastrophic consequences. My vehicle has now less than 3,000 miles. Updated 10/03/08.
Passenger airbag sensor stays in "off" position when my daughter - who is 5'7" and 136 lbs. - is in the seat. We have driven the car over long distances and I slammed on the brakes hard enough to employ the abs, to no avail. The sensor continues to stay in the "off" position.