What Does B0055 Mean?
DTC B0055 indicates the Body Control Module (BCM) has detected a fault in the second row right seatbelt buckle sensor circuit. This sensor monitors whether the seatbelt is fastened and communicates with the vehicle's occupant restraint system and warning indicator system. The 'subfault' designation suggests a secondary issue such as an intermittent connection, out-of-range signal, or sensor degradation rather than a complete circuit failure.
Common Causes
45%
Faulty seatbelt buckle sensor/switch due to wear, corrosion, or internal electrical failure
30%
Damaged, corroded, or loose wiring connector at the seatbelt buckle or under the seat
15%
Broken or chafed wiring in the harness running from the buckle to the BCM, often due to seat movement
10%
Body Control Module (BCM) internal fault or software corruption affecting seatbelt sensor monitoring
Diagnostic Steps
1
Step 1: Perform a visual inspection of the second row right seatbelt buckle assembly and connector for obvious damage, corrosion, debris, or loose connections. Check that connector is fully seated and terminals are not pushed back or corroded.
2
Step 2: Using a digital multimeter, test the seatbelt buckle sensor continuity with buckle unbuckled and buckled. Typically should show open circuit when unbuckled and closed circuit (0-5 ohms) when buckled. Compare readings to manufacturer specifications.
3
Step 3: Inspect the wiring harness from the buckle connector to under-seat area and along seat tracks for signs of chafing, pinching, or damage caused by seat movement. Wiggle test connectors and wiring while monitoring live data for intermittent faults.
4
Step 4: If wiring and sensor test normally, check voltage supply to the buckle sensor (typically 5V reference) and ground circuit integrity with multimeter. Verify BCM is providing proper reference voltage and ground.
5
Step 5: Clear the DTC code and perform multiple buckle/unbuckle cycles while monitoring live data stream for proper sensor state changes. Test with weight in seat to simulate occupancy if available.
6
Step 6: If all previous tests pass, suspect BCM internal fault. Verify BCM software is up to date and check for Technical Service Bulletins (TSBs) related to seatbelt sensor issues before considering BCM replacement.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
DTC B0055 indicates the Body Control Module (BCM) has detected a fault in the second row right seatbelt buckle sensor circuit. This sensor monitors whether the seatbelt is fastened and communicates with the vehicle's occupant restraint system and warning indicator system. The 'subfault' designation ...
The most common cause of B0055 (Second Row Right Seatbelt Sensor (Subfault)) is: Faulty seatbelt buckle sensor/switch due to wear, corrosion, or internal electrical failure
Typical repair costs for B0055 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is safe to drive, but the seatbelt warning system may not function properly for the second row right passenger, potentially allowing occupants to ride unbuckled without warning. The airbag system itself is not affected, but occupant detection for that seating position may be compromised. Repair within 1-2 weeks to ensure all safety systems function properly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B0055 to identify the root cause.
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Quick Info
Category
Body
System
Occupant Restraint System / Seatbelt Warning System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
