Air bag sensor light blinks 4 times

Hi,

I have a couple of questions:

1. The bag light on a friend's Miata 91 has started to flash 4 times continuously (4 blinks, stop, 4 blinks, and so on). I've seen something about a faulty sensor "S" in
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   but I don't know what that means. Any ideas?

1. This is somewhat James Bond like to me but I've been told that there is some kind of mechanism that allows the front license plate to change position (from vertical to horizontal) so as to allow better air flow. Does anybody know if this exists and if so where I can get a hold of one?

Thanks,

DC.