Damaged or disconnected wiring harness at the second row right seat, often from seat movement or cargo loading; Faulty clock spring or seat belt pretensioner connector in the same circuit (less common for this specific code); Corroded or loose electrical connector at the airbag module or under the seat; Failed second row right frontal airbag stage 1 inflator or module; Internal fault in the restraint control module (SRS module); Aftermarket accessories or spilled liquids affecting the seat wiring

DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B0039

B0039Second Row Right Frontal Stage 1 Deployment Control

Q: What does code B0039 mean?

Second Row Right Frontal Stage 1 Deployment Control. B0039 indicates that the restraint control module has detected a fault in the deployment circuit for the second row right frontal airbag stage 1, which is the first-stage inflator for the passenger-side rear seat. The module monitors circuit resistance and continuity, and it sets this code when the measured values fall outside the expected range or when the circuit is open or shorted.

B0039 indicates that the restraint control module has detected a fault in the deployment circuit for the second row right frontal airbag stage 1, which is the first-stage inflator for the passenger-side rear seat. The module monitors circuit resistance and continuity, and it sets this code when the measured values fall outside the expected range or when the circuit is open or shorted.

SystemBody

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

Airbag warning light illuminated on the instrument cluster
SRS (Supplemental Restraint System) warning message displayed on the driver information center
Often no symptoms besides the warning light, with the airbag system otherwise appearing normal
The second row right frontal airbag may be disabled and will not deploy in a collision
In some vehicles, a chime or reminder that the restraint system requires service

Common causes, most likely first

Damaged or disconnected wiring harness at the second row right seat, often from seat movement or cargo loading
Faulty clock spring or seat belt pretensioner connector in the same circuit (less common for this specific code)
Corroded or loose electrical connector at the airbag module or under the seat
Failed second row right frontal airbag stage 1 inflator or module
Internal fault in the restraint control module (SRS module)
Aftermarket accessories or spilled liquids affecting the seat wiring

How to diagnose and fix it

Inspect the wiring harness and connectors under the second row right seat for damage, corrosion, or loose pins
Disconnect the battery and wait for the system to discharge, then check resistance across the airbag squib circuit with a multimeter
Compare the measured resistance to the manufacturer's specification and check for shorts to ground or power
Substitute a known-good airbag simulator or resistor to isolate whether the fault is in the module or the airbag
If the circuit checks good, diagnose the restraint control module for internal faults using a scan tool with bidirectional controls
Repair or replace the faulty wiring, connector, or airbag component as needed
Clear the code and verify the repair by cycling the ignition and confirming the light stays off

Common misdiagnosis traps for B0039

A common mistake is replacing the airbag module when the real problem is a chafed wire under the seat that only shows up when the seat is moved or loaded.
The code can be set by a loose connector that tests fine at rest but loses contact during driving, so wiggle testing the harness while monitoring resistance is essential.
After a collision repair, this code often appears because the second row right airbag was not reconnected or the wrong airbag was installed.
Some vehicles require the restraint control module to be configured or programmed after replacement, and skipping this step will leave the code stored.
Water leaks or spills near the second row seat can corrode the connector pins and cause intermittent faults that do not appear during a static inspection.

Can I keep driving with B0039?

Because this fault can prevent the second row right frontal airbag from deploying in a crash, the vehicle should not be considered safe for passengers in that seat until repaired. Avoid carrying passengers in the second row right seat and have the system diagnosed promptly by a qualified technician.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.