Faulty seat belt buckle switch or sensor in the third row centre position; Damaged, pinched or chafed wiring where the third row seat folds or slides; Corroded, loose or contaminated connector under the seat or in the rear trim; Dirt, spilt drink or debris inside the buckle affecting the sensor; Wiring damage after seat removal, refitting or a previous repair; Fault in the restraint control module or its software.

B0057

Third Row Center Seat Belt Sensor.

Generic
Body
Generic code
Medium severity

How this code is built

B: SystemBody
0: Defined bySAE, the same on every car
0: AreaBody area 0
57: FaultThe specific fault in that area

What it means

B0057 is the generic code for a fault in the third row centre seat belt sensor, normally the buckle switch that tells the restraint control module whether that belt is fastened. The module saw a signal or circuit reading from this sensor that was out of range, implausible or missing, so it set the code and usually switched on the airbag warning light. The exact fault type (open circuit, short or implausible signal) and the sensor design vary by vehicle, so check the manufacturer data for the model.

Symptoms

Airbag or SRS warning light on the dashboard
Seat belt warning light or chime behaving wrongly for the third row centre seat
Belt reminder showing as fastened or unfastened when it is not
Restraint system self-test fault stored, which may fail an inspection
Intermittent warning that comes and goes with seat movement or when the seat is folded

Possible causes

Faulty seat belt buckle switch or sensor in the third row centre positionlikely
Damaged, pinched or chafed wiring where the third row seat folds or slideslikely
Corroded, loose or contaminated connector under the seat or in the rear trimlikely
Dirt, spilt drink or debris inside the buckle affecting the sensorpossible
Wiring damage after seat removal, refitting or a previous repairpossible
Fault in the restraint control module or its softwarerare

How to diagnose

Read all stored codes and freeze frame data, then note whether B0057 is current or history and whether other restraint codes are present
Check the airbag warning light and the belt warning behaviour for the third row centre seat
Visually inspect the buckle, belt and surrounding trim for damage, dirt or spilt liquid
Inspect the wiring and connector for the third row centre belt for chafing, pinching, corrosion or bent pins, following the manufacturer's SRS safety procedure first
Wiggle-test the harness and buckle with the system powered, watching live data for the belt status changing erratically
With the battery isolated and the manufacturer's waiting time observed, measure the sensor circuit resistance and continuity to the module as specified in the manufacturer data
Check live data for the belt status changing correctly when the buckle is latched and released
Clear the code after repair, cycle the ignition and recheck that it does not return

How to fix

Replace the faulty third row centre seat belt buckle or sensor assembly
Repair or replace damaged wiring, using the manufacturer's approved repair method for SRS circuits
Clean, reseat or replace corroded or damaged connectors
Clean the buckle if contamination is the cause and the manufacturer permits it, otherwise replace it
Replace or update the restraint control module only if the manufacturer's diagnostics confirm it is at fault

Can I keep driving?

Medium severity

The car can usually be driven, but the restraint system may not protect the third row centre occupant correctly, and the airbag light may mean other faults are masked. Avoid carrying a passenger in that seat and book the repair soon.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.