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DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B0090

B0090Driver Side Pretensioner Stage 2 Deployment Control

B0090 indicates that the restraint control module has detected a fault in the deployment circuit for the second stage of the driver-side seat belt pretensioner. The module monitors the circuit's resistance and continuity and sets this code when the signal falls outside the expected range, which can prevent that stage from firing in a crash.

SystemBody
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

  • The airbag or supplemental restraint system warning light is illuminated on the dashboard.
  • Often no symptoms besides the warning light, with the vehicle driving normally.
  • The seat belt may not lock or retract as designed in some failure modes.
  • A stored crash or restraint system fault may appear in the module's memory.
  • In rare cases, the pretensioner may deploy unexpectedly if the circuit is shorted.

Common causes, most likely first

  1. Damaged or chafed wiring in the driver-side pretensioner stage 2 circuit, often at the seat track or door sill.
  2. Corroded or loose electrical connector at the pretensioner or under the seat.
  3. Open or shorted pretensioner stage 2 squib inside the seat belt buckle assembly.
  4. Faulty restraint control module, though this is less common than wiring issues.
  5. Water intrusion or crash damage affecting the pretensioner circuit.
  6. Improperly performed prior repairs that left the circuit disconnected or damaged.

How to diagnose and fix it

  1. Inspect the driver-side seat belt pretensioner connector and wiring for damage, corrosion, or loose pins.
  2. Check for technical service bulletins or recalls related to the pretensioner circuit for the specific vehicle.
  3. Measure the resistance of the stage 2 pretensioner squib with a proper meter and compare to specification.
  4. Perform a wiggle test on the harness while monitoring the circuit to reveal intermittent faults.
  5. Repair or replace damaged wiring and connectors, then clear the code and verify it does not return.
  6. If the circuit tests good, substitute a known-good pretensioner or module to isolate the faulty component.
  7. After repair, clear codes and perform a restraint system verification drive and scan.

What most technicians miss on B0090

  • A common oversight is replacing the pretensioner when the real fault is a chafed wire under the seat that only shows up when the seat is moved.
  • The code can be set by a low battery or voltage spike during jump-starting, so always check for other low-voltage codes before condemning parts.
  • Some vehicles require the battery to be disconnected and a wait period before servicing the pretensioner to avoid accidental deployment.
  • The stage 2 circuit is often separate from stage 1, so a good stage 1 reading does not rule out a stage 2 fault.
  • After any repair, the restraint module may need a learn or reset procedure that a generic scan tool cannot perform.

Can I keep driving with B0090?

Because this fault can prevent the pretensioner from deploying in a crash, the vehicle should not be driven until the circuit is repaired. Avoid any impact to the driver-side seat or door area and have the system diagnosed promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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