Summary
B0100 indicates the airbag control module (ACM) has detected a fault with electronic frontal sensor 1 — the primary front-mounted crash accelerometer that detects frontal collisions. The most common cause is a faulty sensor (40%), followed by wiring or connector problems (30%) and ACM communication faults (15%). When this code is active, the ACM cannot properly discriminate frontal crash severity, which means frontal airbag deployment may be delayed, prevented, or incorrectly staged. The airbag warning light will be on.
Severity: High — frontal airbag deployment timing compromised
Safe to drive: Yes, cautiously — frontal airbags may not deploy or may deploy late in a crash
Repair cost: $150–$700 depending on cause
DIY difficulty: Moderate
What does B0100 mean?
Modern vehicles use distributed crash sensing with satellite sensors mounted at the front of the vehicle in addition to the ACM's internal accelerometer. Electronic frontal sensor 1 is typically mounted behind the front bumper reinforcement, on the radiator support, or in the front fender area. It provides early crash detection data to the ACM, allowing the system to determine crash severity and direction faster than the centrally-located ACM accelerometer alone.
B0100 is set when the ACM detects a communication failure, signal error, or self-test failure from this primary frontal sensor. The sensor communicates with the ACM via a dedicated wire pair or LIN bus, and the ACM continuously monitors the connection. When the sensor fails to respond, sends invalid data, or the communication line has a fault, the ACM flags the code and may limit or disable frontal airbag deployment capability.
The frontal crash sensor data is used by the ACM to make rapid deployment decisions — in as little as 15–30 milliseconds after impact. Without sensor 1's input, the ACM must rely solely on its internal accelerometer, which provides less crash discrimination capability. This can result in delayed deployment, non-deployment, or inappropriate deployment force staging.