Drivers typically notice one or more of the following when the B0055 code is present:
These alerts appear only for the affected seat; all other seats and vehicle functions operate normally. Because the fault is confined to the supplemental restraint system (SRS), there are no symptoms such as rough idle, loss of power, or illumination of engine‑related warning lights.
The seat‑belt sensor uses a resistance‑based switch to detect buckling. A broken wire, corroded connector, or internal short can cause the sensor to read “unbuckled” continuously, prompting the BCM to flag B0055.
Mechanical wear, exposure to extreme temperatures, or manufacturing defects may cause the sensor’s internal switch to fail. When the sensor cannot generate a valid signal, the BCM interprets the condition as a fault.
The seat‑belt sensor is typically wired to the Body Control Module (or a dedicated SRS control unit). Corrosion, poor grounding, or a damaged BCM I/O driver can interrupt the data flow, resulting in the same diagnostic code even though the sensor itself is functional.
Occasionally, a corrupted calibration table within the BCM can misinterpret a valid sensor voltage as an error. Re‑programming the module often clears the false code.
Connect a scan tool that supports SRS/BCM diagnostics. Verify that B0055 is present and note any additional SRS codes (e.g., B0050‑B0059 series) that may indicate a broader communication issue.
– Locate the second‑row right seat‑belt sensor (usually mounted in the seat frame).
– Inspect the wiring harness for frayed conductors, pinched sections, or corrosion at the connector.
– Ensure the connector clips are fully seated and the pins are clean.
With the ignition off, disconnect the sensor connector and measure resistance across the sensor terminals. A healthy sensor typically reads between 200 Ω and 400 Ω when buckled and near infinite resistance when unbuckled. Values outside this range suggest a faulty sensor.
Using a multimeter, verify continuity from the sensor connector to the BCM input pin. An open circuit confirms a wiring fault; a short to ground or power indicates a harness defect.
Many professional scan tools can command a “BCM communication test” or “module ping.” A failure here points to a BCM I/O driver problem rather than the sensor itself.
If the hardware checks out, re‑flash the BCM with the latest SRS software version. This step addresses possible calibration errors and clears lingering fault memory.
– Sensor Replacement: Only after confirming a defective sensor and a healthy BCM should the sensor be swapped.
– BCM Replacement: When the BCM fails the communication test or shows internal damage, replace the module. Because the BCM houses the seat‑belt sensor interface, a new module restores both the sensor circuit and the SRS logic.
*Flagship One offers VIN‑matched control modules that are pre‑programmed to your vehicle’s specifications. A replacement BCM from Flagship One includes a plug‑and‑drive warranty, ensuring correct calibration and immediate compatibility.*
After repair or replacement, clear all codes with the scan tool. Conduct a functional test: fasten the second‑row right seat belt, observe the chime, and confirm that the SRS lamp extinguishes. Repeat the test with the belt unbuckled to ensure the warning re‑activates appropriately.
Estimated Costs
Service Recommendation: Most issues related to this fault are diagnosed and corrected through inspection, wiring repair, and calibration rather than module replacement. For modules not typically replaced through aftermarket suppliers, diagnosis and repair should be performed by a certified automotive technician with access to factory service information and tooling.