Owners manual says that if you disconnect the battery for more than a short time, the air bag light will come on, and you have to go to a dealer to have it reset. I'm sure there's an easier/cheap way to go, but I haven't researched it yet myself.
(Probably nothing wrong with airbag thing, just has to be reset)
You can also clear codes by just pulling the EFI fuse out of the underhood fuse panel. It may come back on after a bit, or it may not. (as in my case)
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Domesticon Prime

93' LE V-6, 303K Km., fully optioned including Leather Interior. ES300 rear discs, twin piston front calipers, Depo Chromes with HID projectors, 17" OZ' summer's, 96 corner lights, MAF, timing, exhaust and intake mods, 2001 Toyota/JBL sound, + more and always more coming.