I found this on the web and it worked perfectly for me. The problem reoccurred about 4 months later. I just repeated the exercise and it has been OK since. I printed off these instructions and put them in my glovebox!
1. Turn ignition key part way so that lights on dash come on but don't start the engine.
2. Watch the airbag light closely. It will stay on for a few seconds and as soon as it blinks off turn the key to off INSTANTLY.
3. Count to 5.
4. Repeat steps 1-3 above twice so that you have completed this cycle 3 times.
5. Turn the key again and watch the light. It should start blinking more slowly. This is in diagnostic mode. No need to hurry this time, but turn off and count to 5 again.
6. This should do the trick, if not, have another go.
Good luck
Rob
January 2009