Damaged, corroded or loose connector at the second row left seat or pillar, often from seat movement or items stowed underneath; Open circuit or chafed wiring in the harness to the second row left deployment device; Faulty deployment device (squib, pretensioner or airbag module) with out-of-range resistance; Poor connection at the SRS control unit connector or an intermediate connector; Wiring disturbed after previous bodywork, trim or seat removal work, or after a collision repair; Fault within the SRS control unit; Water ingress or corrosion in the floor or seat area affecting the circuit.

B0031

Second Row Left Frontal Stage 1 Deployment Control.

Generic
Body
Generic code
High severity

How this code is built

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

What it means

B0031 is the generic SAE J2012 code for a fault in the second row left frontal stage 1 deployment control circuit. The restraint control unit (SRS module) runs self-tests on the deployment loop, and it set this code because it saw an abnormal resistance, an open circuit or a short in that circuit. What is fitted at this position (a seat-mounted airbag, a belt pretensioner or another device) depends on the model, so check the manufacturer's wiring information for the vehicle.

Symptoms

Airbag or SRS warning light on the dashboard
Possible message about a restraint system fault
The second row left restraint may not deploy in a crash
Fault may be intermittent and appear after the seat has been moved, folded or occupied
Other SRS fault codes stored alongside it
Failed MOT or inspection because of the SRS warning light

Possible causes

Damaged, corroded or loose connector at the second row left seat or pillar, often from seat movement or items stowed underneathlikely
Open circuit or chafed wiring in the harness to the second row left deployment devicelikely
Faulty deployment device (squib, pretensioner or airbag module) with out-of-range resistancepossible
Poor connection at the SRS control unit connector or an intermediate connectorpossible
Wiring disturbed after previous bodywork, trim or seat removal work, or after a collision repairpossible
Fault within the SRS control unitrare
Water ingress or corrosion in the floor or seat area affecting the circuitrare

How to diagnose

Read all stored and pending codes and any freeze frame data, noting whether the fault is current, intermittent or history only
Check for other SRS codes that point to a shared connector, a wiring section or a recent event
Inspect the second row left seat, trim and floor area for damage, moisture, trapped wiring or signs of previous repair
Visually inspect the connector at the second row left device and the yellow SRS connectors along the harness for bent pins, corrosion and a secure locking tab
Following the manufacturer's procedure, isolate the battery and wait the specified time before disconnecting any SRS connector, and never probe or test deployment devices with a standard meter or test lamp
Check the harness resistance and continuity only with the method and specification given for that model, with the device disconnected
Wiggle-test the harness and connectors with live data on view to find an intermittent fault, following the manufacturer's safety procedure
After repair, clear the code and confirm the SRS light goes out and the code does not return

How to fix

Repair or replace damaged wiring, using the approved repair method for SRS circuits
Clean, re-seat or replace a corroded or damaged connector or terminal
Replace the faulty second row left deployment device if the circuit checks point to it
Refit and secure the harness correctly where it was pinched, stretched or disturbed by seat or trim work
Replace the SRS control unit only if the manufacturer's diagnosis confirms it is faulty, and carry out any required coding or setup

Can I keep driving?

High severity

The car may still drive normally, but the second row left restraint may not work in a crash, so limit use, especially with a passenger in that seat. Book it in for prompt repair by a technician qualified to work on SRS systems.

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