Code 12
WARNING: This page is about a different car, the 1995 Toyota Paseo. However, it is still accessible from the selected car via links, so may be relevant.
Indicates short to battery voltage in circuit between center air bag sensor and either air bag; faulty air bag; short to battery voltage in +S circuit between front air bag sensor and center air bag sensor; open circuit between front air bag sensor and center air bag sensor, faulty spiral cable; or faulty center air bag sensor.