EN

Severity: High Code type: Generic (all makes) ✱

B0057 Code: 3rd Row Center Belt Sensor (GM: Passenger Pretensioner)

SAE: third-row middle buckle sensor fault. GM: fault in the front passenger belt pretensioner firing loop.

Unverified: this manufacturer-specific definition comes from a single source or varies by model. Confirm it with a brand-specific scan tool.

Safety first · Consult a professional

  • Airbag (SRS) circuits must only be serviced by a professional. Never probe airbag connectors — accidental deployment causes serious injury.

At a glance

Severity: 4/5 – High4/5

Severity: High

Meaning
3rd Row Center Belt Sensor (GM: Passenger Pretensioner)
System
Body Systems · Body
Safe to drive?
With caution
Typical repair cost
$100–$1,300
DIY difficulty
Professional only

B0057 is defined differently by different makers, so this page is marked unverified. The SAE J2012 list assigns it to the third row center seatbelt sensor, the buckle switch for the middle seat in the third row of larger SUVs and minivans that monitor rear belt use. GM uses the number for the right front (passenger) seatbelt pretensioner deployment loop, typically reported as resistance low: the pretensioner is a small pyrotechnic charge in the belt retractor at the base of the B-pillar or in the buckle, which yanks the belt tight at the start of a crash. On a GM vehicle the module has usually disabled that pretensioner, so the passenger belt will not tighten in a collision. For the SAE meaning, folding or removing third-row seats and cargo pressing on the middle buckle are the usual triggers.

How to read B0057

How to read B0057B10203574
  1. B Body
  2. 0 Generic (SAE)
  3. 0 Body Systems
  4. 57 Specific fault

Symptoms

  • Airbag warning light on
  • GM: code appeared after the lower B-pillar trim, carpet or passenger seatbelt was removed
  • GM: passenger belt locked and won't retract after a minor impact (fired pretensioner)
  • Third-row middle belt reminder wrong on the dash display
  • Code set after third-row seats were folded, stowed or taken out

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. GM: pretensioner connector at the lower B-pillar disturbed, corroded or not latched 28%
  2. SAE meaning: third-row center buckle or its wiring damaged by folding seats or cargo 22%
  3. GM: passenger pretensioner out of range or already fired 18%
  4. Removable or stow-away third-row seat contacts dirty or misaligned 12%
  5. Water in the floor area corroding connectors (leaking door seal or rear hatch) 12%
  6. Airbag control module fault 8%

Diagnosis step by step

Diagnostic flow: B00571Get the manufacturer's description2GM: check the passenger belt3SAE: check the third row4Never test a pretensioner yourself5Shop loop test and repair6Confirm the fix

  1. Get the manufacturer's description

    Read the airbag module with a tool that shows make-specific text and the failure subtype. 'Passenger pretensioner loop' sends you to the B-pillar; 'third row center seatbelt sensor' sends you to the back of the vehicle.

    Tools: OBD-II scanner

  2. GM: check the passenger belt

    Pull the passenger belt out and let it retract. A belt that's locked, sits unusually tight or has a scorched retractor area suggests the pretensioner has already fired and must be replaced.

  3. SAE: check the third row

    Make sure the middle third-row seat is fully latched in its seating position and nothing is resting on the buckle. On removable seats, look for dirty or bent floor contacts before visiting the shop.

    Tools: Flashlight

  4. Never test a pretensioner yourself

    A pretensioner is an explosive device just like an airbag. Probing its plug with a meter or test light can fire it; the shop disconnects the battery and waits the specified time before removing the B-pillar trim.

  5. Shop loop test and repair

    The technician fits a simulator at the pretensioner or checks the buckle sensor's live status, depending on the definition. Faulty pretensioners and buckles are replaced as assemblies; wiring gets SRS-approved repairs.

    Tools: OBD-II scanner

  6. Confirm the fix

    After clearing the code with nobody in the car during battery reconnection, the SRS lamp must go out. For the third-row meaning, the belt reminder must show the correct status for that seat.

    Tools: OBD-II scanner

Repair options & costs

RepairDIY?Estimated cost
SRS diagnosis with make-specific scan tool No $100–$200
Repair pretensioner or buckle connector No $100–$300
GM: replace passenger seatbelt retractor with pretensioner No $300–$800
Replace third-row center buckle No $150–$400
Replace airbag control module No $500–$1,300

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Notes by brand

Chevrolet

On Chevrolet models B0057 refers to the right front (passenger) seatbelt pretensioner deployment loop, commonly with a low-resistance subtype. The connector sits behind the lower B-pillar trim.

Emissions / smog test impact

Depends

The US emissions test isn't affected. States with safety inspections may fail a car with the airbag light on or a seatbelt that doesn't retract properly.

Frequently asked questions

What is a seatbelt pretensioner?

A small pyrotechnic device in the belt retractor or buckle that pulls the belt tight in the first milliseconds of a crash. It's monitored by the airbag module just like an airbag.

My passenger belt won't retract after a small bump. Is that B0057?

On a GM vehicle it can be. If the pretensioner fired, the belt often stays locked and the loop reads out of range. The retractor must be replaced, and the module checked for crash data.

Why would a third-row seat set an airbag light?

Some vehicles monitor rear belts for the belt reminder and report faults through the airbag module. A damaged buckle or poor seat contacts in the third row can then trigger B0057 under the SAE definition.

Which meaning applies to my car?

Only a scan tool that reads your manufacturer's code text can tell. GM vehicles use the pretensioner meaning; many others follow the SAE third-row definition.

Sources