Not assigned in the generic OBD-II standard - if your scan tool shows this code, it is manufacturer-specific; verify the meaning in your make's service information

Airbag ECU malfunction is often caused by a faulty front impact sensor or corroded connector under the bumper. Inspect the driver-side and passenger-side impact sensor connectors first. Water intrusion from a missing fender liner is the usual root cause on these trucks. If connectors are clean, the SDM (Sensing and Diagnostic Module) itself may need replacement. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN.

Check the clockspring in the steering column first -- it connects the airbag module and fails with age. Symptoms include airbag light plus horn and steering wheel button failures. If the clockspring is fine, inspect the passenger seat occupant sensor mat. Ford extended warranty on the occupant sensor for some 2009-2014 models (SSM 47240).

Toyota airbag ECU codes are commonly triggered by a faulty spiral cable (clockspring) or a driver-side airbag connector that works loose. Start by reseating the yellow airbag connectors under the seats -- these vibrate loose over time. If B0100 persists, the airbag ECU behind the center console may need replacement. Always disconnect the battery and wait 90 seconds before working on airbag circuits.