Two problems related to side/window air bag have been reported for the 2008 Mazda MAZDA3. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Mazda MAZDA3 based on all problems reported for the 2008 MAZDA3.
Turning left on a t junction when some one ran a red light and crashed into my driverside front and rear doors. The hit was hard enough to pin the steering wheel with the smashed in door, but the side airbags did not go off. No corrective action was taken as the vehicle was titled as a total loss.
The front passenger seat weight sensors are programmed to inactivate the front and side passenger air bags and the front passenger seat belt pretensioner if the front passenger weighs between 66 and 93 lbs. My wife weighs about 83 lbs. According to Mazda, this is not a defect, but a federal government requirement. I can understand the side air bag inactivation, but not the front air bag inactivation (you can push the seat far back) and certainly not the seat belt pretensioner inactivation. This rule is wrong and puts lives at risk. If you google "Mazda front air bag inactivation", you will see that lots of Mazda owners have the same complaint, and it extends to owners of other makes. The air bag inactivation light continues to go on and off as my wife moves in her seat, and has done this since the car was new. We have a 2006 Mazda3 with exactly the same problem.