Damaged or disconnected connector at the rear left airbag or inflator, often from rear seat or trim work; Wiring fault between the airbag control unit and the second row left airbag, such as chafing, an open circuit or a short in the B-pillar, door shut area or under the seat; Corroded or loose terminals, or a faulty clock spring-type connection or in-line connector in the circuit; Faulty or incorrectly fitted side or curtain airbag module (inflator resistance out of range); Low battery voltage or a poor earth causing the self-test to fail; Fault inside the airbag control unit, or a crash-stored fault that has not been cleared.

B0030

Second Row Left Side Airbag 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
30: FaultThe specific fault in that area

What it means

B0030 means the airbag control unit has found a fault in the deployment control circuit for the second row left side airbag. This is the circuit that fires the airbag or curtain inflator on that side. The unit runs a self-test and sets the code when it sees abnormal resistance, an open circuit, a short to ground or to voltage, or a wrong inflator signature. Exact wiring and the airbag fitted (side, curtain or both) depend on the model.

Symptoms

Airbag warning light on the dashboard, either lit constantly or flashing
Rear left side or curtain airbag may not deploy in a crash
Airbag fault message on the instrument cluster in some models
Seat belt pretensioner or other side airbag faults stored at the same time
Fault returning after clearing, sometimes after the rear seat or trim has been moved

Possible causes

Damaged or disconnected connector at the rear left airbag or inflator, often from rear seat or trim worklikely
Wiring fault between the airbag control unit and the second row left airbag, such as chafing, an open circuit or a short in the B-pillar, door shut area or under the seatlikely
Corroded or loose terminals, or a faulty clock spring-type connection or in-line connector in the circuitpossible
Faulty or incorrectly fitted side or curtain airbag module (inflator resistance out of range)possible
Low battery voltage or a poor earth causing the self-test to failpossible
Fault inside the airbag control unit, or a crash-stored fault that has not been clearedrare

How to diagnose

Read all stored codes and freeze frame data, noting whether B0030 is current or history and whether other airbag codes are present
Ask about recent crash damage, seat removal, upholstery work or trim work in the rear left area
Check battery condition and charging voltage, and rectify low voltage before further diagnosis
Following the manufacturer's safety procedure (isolate the battery and wait the specified time), visually inspect the rear left airbag connector, in-line connectors and harness for damage, pinched cable or corrosion
Check connector locks, shorting clips and terminal tension, and that the connector is fully seated
Check the harness for continuity and shorts to ground or voltage using the manufacturer's wiring diagram, with the airbag unplugged; never probe or measure an airbag module directly with a test meter
Compare the live airbag circuit resistance and status data with specification where the model allows it, using a suitable scan tool
Clear the code only after repair, then recheck that it does not return

How to fix

Reseat, clean or replace damaged connectors and terminals in the second row left airbag circuit
Repair or replace damaged wiring, following the manufacturer's repair procedure for airbag harnesses
Correct trim, seat or harness routing that is trapping or stretching the wiring
Replace the faulty airbag module or inflator if it is confirmed as the cause, using the correct part for the vehicle
Repair the battery or earth fault if low voltage caused the fault
Replace or reprogram the airbag control unit only if the manufacturer's diagnosis confirms it as faulty

Can I keep driving?

High severity

The car can be driven carefully to a workshop, but the rear left side airbag may not work in a crash, so book the repair urgently. Avoid carrying passengers in the rear left seat until it has been fixed.

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