OBD-II trouble code
B003B: Second Row Right Frontal Stage 3 Deployment Control (Subfault)
The airbag/SRS control module detected an electrical fault in the second-row right frontal airbag's stage 3 deployment loop. That airbag may not deploy 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 B003B mean?
B003B is a body (B) code stored by the airbag control module. It is a hexadecimal code — the character after B003 is the letter A's successor B, not a number — and its SAE-generic definition is 'Second Row Right Frontal Stage 3 Deployment Control,' referring to the firing loop that deploys the third stage of a frontal airbag protecting the right-side second-row seating position. It is the stage 3 companion of B0039 (Stage 1) and B003A (Stage 2) on the same airbag, and the right-side mirror of B0033 (Second Row Left Frontal Stage 3). A second-row frontal airbag is uncommon, so confirm the exact application against your make's service data before assuming the airbag is fitted. Multi-stage airbags fire in steps so the module can tailor deployment force to crash severity; stage 3 is typically the highest-force stage used in the most severe impacts.
The module sets the code when the stage 3 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 second-row airbag's firing loop runs through connectors under or beside the rear seat that are easily disturbed by folding the seat, adjusting it, or trim service, those connectors and any harness disturbed during rear-area work are the most common trouble spots. When all three stage codes for one airbag set together, suspect a shared connector, ground, or the airbag itself rather than three separate failures.
This is a supplemental restraint fault, not a driveability fault: the vehicle drives normally, but the second-row right frontal airbag may not deploy as intended 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 near the second-row right seat
- Damaged wiring in the frontal-airbag loop after seat folding, adjustment, or removal
- Failed second-row frontal airbag inflator or its stage 3 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 B003B 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 folded or moved
Diagnostic steps
- 1.Use a scan tool that can access the airbag/SRS module and record B003B with its full symptom byte and any companion codes such as B0039 or B003A.
- 2.Confirm the vehicle actually has a second-row right frontal airbag — it is uncommon — and locate its connector for the specific make and model.
- 3.With the system safely disabled per service procedure, inspect the seat and connector for corrosion, backed-out terminals, or crush damage.
- 4.Fold and adjust the second-row seat while watching for an intermittent fault, since these loops are commonly disturbed by seat movement.
- 5.Measure the deployment-loop resistance against specification to separate a wiring/connector fault from a failed inflator.
- 6.If all three stage codes (B0039/B003A/B003B) are present, focus on the shared connector, ground, and the airbag itself rather than three separate squibs.
- 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 seat connector can be inexpensive, while a failed airbag or control module is much costlier. SRS diagnostic time typically runs $100-$200, and a second-row 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.