OBD-II trouble code
B003A: Second Row Right Frontal Stage 2 Deployment Control (Subfault)
The airbag/SRS control module detected an electrical fault in the second-row right frontal airbag's stage 2 deployment loop. That rear frontal airbag may not deploy at full force as designed, so this needs prompt professional attention.
Quick facts
- System
- Body
- Category
- Airbag / SRS Restraints
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $900
- DIY difficulty
- Shop recommended
What does B003A mean?
B003A is a body (B) code stored by the airbag control module. B003A is a hexadecimal code (the character after 'B003' is the letter A, not a zero) and its SAE-generic definition is 'Second Row Right Frontal Stage 2 Deployment Control,' referring to the firing loop that deploys the second stage of the frontal airbag protecting the right-side second-row (rear) seating position. It is the stage 2 companion of B0039 (Stage 1) and the right-side mirror of B0032 (Second Row Left Frontal Stage 2). Multi-stage airbags fire in steps so the module can tailor deployment force to crash severity — stage 2 adds full force for more severe impacts. Not every vehicle has a second-row frontal airbag, so confirm the exact application against your make's service data.
The module sets the code when the stage 2 deployment loop's resistance falls outside the tight window these pyrotechnic circuits require — an open circuit, a short to power or ground, or resistance that is too high or too low. A symptom byte appended to the code identifies the exact fault type. Because a rear frontal airbag's firing loop runs through under-seat and seat-frame connectors that flex as the seat is adjusted, folded, or removed, those connectors and any harness disturbed during seat or trim service are the most common trouble spots. If both B0039 and B003A are stored, suspect a shared connector, ground, or the airbag itself rather than two separately failed stages.
This is a supplemental restraint fault, not a driveability fault: the vehicle drives normally, but the second-row right frontal airbag may not deploy at full designed force in a crash, and airbag circuits carry a small risk of unintended deployment when mishandled. SRS diagnosis and repair should be performed by a qualified technician who can safely disable the system, and the fault should not be left unrepaired.
Common causes
- Corroded, backed-out, or loose connector under the second-row right seat
- Damaged wiring in the rear frontal-airbag loop after seat removal, folding, or cargo damage
- Failed second-row frontal airbag inflator or its stage 2 squib
- Fault in the SRS connector or its shorting bar at the airbag
- Prior frontal-impact damage or repair that disturbed the loop
- Faulty airbag/SRS control module
Symptoms
- Airbag / SRS warning light on
- Stored B003A fault (often with a symptom byte) in the restraints module
- No effect on engine or driving performance
- Fault that may appear or clear as the second-row seat is moved or folded
Diagnostic steps
- 1.Use a scan tool that can access the airbag/SRS module and record B003A with its full symptom byte and any companion codes such as B0039.
- 2.Confirm the vehicle actually has a second-row frontal airbag and locate its connector for the specific make and model.
- 3.With the system safely disabled per service procedure, inspect the under-seat connector and the seat-frame harness for corrosion, backed-out terminals, or crush damage.
- 4.Fold and adjust the seat while watching for an intermittent fault, since these loops are commonly disturbed by seat movement or recent seat service.
- 5.Measure the deployment-loop resistance against specification to separate a wiring/connector fault from a failed inflator.
- 6.If both frontal stages set together, focus on the shared connector, ground, and the airbag assembly rather than individual stages.
- 7.Repair the wiring/connector fault or replace the indicated component, then clear codes and confirm the SRS light stays off.
Repair cost
$100 – $900
Reseating or repairing the under-seat connector can be inexpensive, while a failed multi-stage airbag or control module is much costlier. SRS diagnostic time typically runs $100-$200, and a rear frontal airbag or SDM/RCM replacement with programming can reach several hundred dollars or more. SRS work should be done by a qualified technician.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with airbag control module (sdm) replacement / reset preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.