B0100 is GM's code for a performance fault in electronic front end sensor 1, the crash sensor on the left side of the front structure. The sensing and diagnostic module powers that sensor, grounds it, and listens for a steady stream of status messages on a two wire line. When those messages stop arriving or never start, the module stores B0100 and turns on the air bag indicator.
GM calls the part an electronic frontal sensor, and its interface is different from a normal squib circuit. The sensor talks rather than sitting there as a resistance. It modulates current on a unidirectional two wire circuit to send an identification message, a state of health message, and, in a crash, a deployment command. The SDM supplies both the power and the ground on that same pair, which is why a single corroded pin takes the whole conversation down.
The module runs the check with ignition voltage between 9 and 16 volts. B0100 sets when a valid identification message does not arrive within five seconds of the sensor being powered up, when more than 375 milliseconds pass with no status message, or when the SDM has already reset the sensor twice without getting a valid identification back. Resetting here means cutting power to the sensor and restoring it, which the module does on its own before it gives up and stores the code.
The neighboring numbers narrow the fault down. B0101 and B0102 cover a sensor whose identification does not match what the SDM has stored and a sensor returning a not-OK message. B0103 through B0105 are the same three faults on electronic front end sensor 2, the right side. GM clears the code when the condition goes away or after 255 fault free ignition cycles, so on some platforms the light stays on for a while after the repair.
Hardware. B0100 reports on a sensor and the two wires feeding it, and nothing in the code refers to an impact. It sets on vehicles that have never been touched.
The overlap comes after a collision. A front hit takes out these sensors and their harnesses, so B0100 often sits next to a locked crash record on the same vehicle. Those are two separate repairs, and the sensor and its wiring come first.
No. A module reset returns the SDM's memory to a factory state and clears stored crash data. It does nothing to a corroded connector or a dead sensor, so B0100 sets again as soon as the module powers the sensor back up.
Repair the circuit first, then decide what the module needs. If the vehicle was in an accident and the SDM also locked with crash data, that side is our work: send the module in for an airbag module reset. Genuine OEM impact sensors are searchable by vehicle in the parts store.
This is GM's numbering. Our Buick code table carries it, and the same code and the same diagnostic sit behind Chevrolet, GMC, Cadillac, Pontiac, and Saturn vehicles of the same era, since those divisions share the SDM and the sensor design. B0100 belongs to the older GM code set. On Global A vehicles the front impact sensors report as B0083 for the left and B0084 for the right instead, so the code you get depends on the platform as much as the badge on the grille.
Read the code with its symptom byte if the scan tool reports one, then get eyes on the sensor. On most of these vehicles it is mounted low in the front structure near the radiator support, where water and salt reach it. Unplug the connector, look at the pins for green or white corrosion, and check the harness where it passes the frame or the bumper beam for chafe damage. If the right side circuit is healthy, compare the two.
If a sensor was already replaced and the code stayed, confirm the part number matches the vehicle, because a mismatched sensor sets B0101 or B0102 rather than curing anything. Related codes are B0103 for the right front sensor and B0083 on the later numbering. When your year and model are not listed in the parts store, send us a part request.
Related codes: B0103, B0083, B0091
Keep reading:
Code scope: Buick. The same number can mean something different on another manufacturer, so match the code to your make before you act on it.
A reset clears stored crash data. A replacement part fixes a hardware fault. We have read these codes since the nineties and will tell you which one you are looking at.
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