B0057: Third Row Center Seat‑Belt Sensor Fault
Does not affect engine or driving performance but impacts safety‑related systems (seat‑belt/SRS)
Overview
B0057 indicates a fault with the third‑row center seat‑belt sensor circuit, commonly causing a persistent seat‑belt reminder and potential airbag/passenger restraint disablement; requires diagnostic inspection of sensor, wiring, and control module.
Common Symptoms
- Third‑row center seat‑belt reminder light remains on
- Continuous chime even when belt is fastened
- SRS/Airbag warning light may illuminate
- Possible disablement of passenger airbag for that seat
Most Common Causes
Sensor fails to change voltage when belt is latched
Open, short, or poor connection interrupts signal to BCM
Module may misinterpret signal or have internal faults leading to false trigger
BCM calibration might not include sensor logic, causing false code
Diagnostic Steps
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Confirm B0057 presence with a professional OBD‑II scanner supporting SRS/BCM codesExpected: B0057 logged, note any additional SRS/seat‑belt related codesInterpretation: Ensures accurate code retrieval and identifies if secondary codes exist
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Perform visual inspection of third‑row center seat‑belt sensor and wiring harness/connectorsExpected: No obvious damage, corrosion, loose pins, or worn insulationInterpretation: If issues present, likely cause; proceed to repair wiring/connectors
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Test sensor circuit voltage/resistance with multimeter when belt is unlatched and latchedExpected: Voltage change (approx. 12V to low) each stateInterpretation: No change indicates sensor or wiring circuit fault
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Verify BCM/SRS module receives and interprets sensor signal using advanced scan toolExpected: Proper signal reading in the moduleInterpretation: If module unresponsive or misinterpreting signal, may be BCM/SRS fault
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Clear codes and re‑scan after repair actionsExpected: Codes do not return and warnings extinguishInterpretation: Successful remediation
Repair Solutions
Typical part cost; requires post‑repair verification
Labor varies with access difficulty
Programming costs and module price vary by vehicle; may require dealer tooling
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Assuming general airbag module fault without checking seat‑belt sensor circuit
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