Airbags

B004A — Third Row Right Frontal Airbag Stage 2 Deployment Control Circuit Fault

Severity: high Drive with care, to a shop

What B004A means

The supplemental restraint system (SRS) module self-tests its airbag circuits and found a problem in the one that controls stage 2 deployment of the third row right frontal airbag. It normally checks circuit resistance and looks for opens, shorts and poor connections. When readings fall outside limits, it stores the code and turns on the airbag light. Exact wording of this code can vary by manufacturer.

Symptoms

  • Airbag/SRS warning light is on
  • Other airbag-related codes may be stored
  • Light may come on intermittently after bumps
  • Warning light may behave abnormally at key-on

Possible causes

  1. Poor contact or corrosion at a connector under the seat or in the third row area
  2. Open or shorted wiring in the airbag circuit
  3. Damaged harness or contacts after seat removal, folding, or interior repair
  4. Faulty airbag module (squib or inflator) in the third row
  5. Faulty SRS control module
  6. Water intrusion causing corrosion in connectors

How to diagnose

  1. Scan all modules with an SRS-capable tool and record freeze-frame and other airbag codes
  2. Ask about recent seat work, interior repairs or water leaks
  3. Disconnect the battery and wait as the manufacturer specifies to avoid accidental deployment
  4. Inspect third row right connectors and harness for damage, corrosion and loose fit
  5. Check circuit resistance and shorts to ground or power per the factory wiring diagram
  6. Use the manufacturer-approved test load or known-good part if the procedure allows
  7. Clear codes and recheck to see if the fault returns

Common fixes

  • Repair the connection or replace a damaged connector or harness section
  • Replace the airbag module or related component if the circuit fault is confirmed
  • Replace or reprogram the SRS module if it is the verified cause
  • Clear codes and verify the system after repair

Questions and answers

Is it safe to drive with B004A?

The car will usually drive, but that airbag may not deploy in a crash. Don't delay diagnosis and avoid seating anyone in that spot if possible.

Can I fix B004A myself?

Working on airbag circuits risks accidental deployment. A visual check is fine, but further work is best left to a technician with proper tools and wiring diagrams.

Why did the airbag light come on after interior work?

A connector under the seat may not be fully seated or a harness may be damaged. Check the connection and rescan for codes.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.