OBD-II trouble code
B0013: Passenger Knee Bolster Deployment Control (Subfault)
The airbag/SRS control module detected an electrical fault in the passenger knee-airbag (knee bolster) firing loop. The passenger knee 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 B0013 mean?
B0013 is a body (B) code stored by the airbag control module — the SDM (sensing and diagnostic module) on GM, or the RCM (restraints control module) on many other makes. Its SAE-generic definition is 'Passenger Knee Bolster Deployment Control,' referring to the firing loop for the passenger-side knee airbag. The knee airbag deploys from the lower dash to cushion the occupant's knees and lower legs and help keep the body properly positioned so the frontal airbag and seat belt work as designed. The module monitors this loop continuously and stores B0013 when its electrical condition is out of specification. On some makes the equivalent circuit is labeled a squib control circuit; confirm the exact application against your vehicle's service data.
The module sets the code when the 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. The knee airbag mounts low in the passenger-side dash, near the footwell, so its firing loop and connector are exposed to that area — a spot where connectors can be kicked, disturbed during lower-dash or knee-bolster panel work, or affected by moisture from wet floor mats.
This is a supplemental restraint fault, not a driveability fault: the vehicle drives normally, but the passenger knee 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 at the passenger knee airbag (low in the dash/footwell)
- Damaged wiring in the knee bolster firing loop
- Failed knee airbag inflator (squib)
- Fault in the SRS connector or its shorting bar at the airbag
- Connector disturbed by lower-dash, knee-bolster panel, or footwell work
- Faulty airbag/SRS control module (SDM/RCM)
Symptoms
- Airbag / SRS warning light on
- Stored B0013 fault (often with a symptom byte) in the restraints module
- No effect on engine or driving performance
- Possible additional passenger-side restraint codes stored alongside it
Diagnostic steps
- 1.Use a scan tool that can access the airbag/SRS module and record B0013 with its full symptom byte and any companion codes.
- 2.Confirm the knee airbag loop routing and connector location for the specific make and model.
- 3.With the system safely disabled per service procedure, inspect the knee airbag connector low in the dash for corrosion, backed-out terminals, kick damage, or moisture.
- 4.Check for recent lower-dash, knee-bolster, or footwell work that could have disturbed the connector.
- 5.Measure the deployment-loop resistance against specification to separate a wiring/connector fault from a failed inflator.
- 6.If the airbag or module was recently replaced, verify the correct part and proper programming.
- 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
A connector repair low in the dash can be modest, while a failed knee airbag inflator or control module is much costlier. SRS diagnostic time typically runs $100-$200, and a knee 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.