Thought I'd share a fix for a common fault on prior Mazda 6 models. Our 2008 Mazda 6 wagon occasionally shows airbag fault code 23. The air bag light flashes 2 times, then 3 times, then repeats after a short delay.

In my case (and others I've seen on other sites) the fault is simply resolved by:
1. Switch off the ignition and remove the key.
2. Slide the passenger seat all the way forward.
3. Enter from the back door and you will see a yellow plug under the seat. This is the air bag wire for the in-seat side airbag.
4. Unplug by pressing the tab and pulling the 2 halves apart, then reconnect, pushing firmly to seat.
5. Start the car and hopefully the fault is cleared.

The latest occurrence was after replacing the car's battery but prior to that is came on for no apparent reason. I have no idea why this fixes the problem.

 

Its a common problem with the 2008-2012 GH Mazda 6's.
To be safe, you should always disconnect the battery and pump the brake pedal a few times before unplugging airbag connectors.