01 The Future of Cars: What Driving Will Look Like in 10 Years • 02 How to Temporarily Fix a Car Water Pump Leak • 03 P0056 – O2 Heater Circuit Fault (Bank 2 Sensor 2): Diagnosi… • 04 Petrol vs Diesel: This is Why You Should Consider a Petrol … • 05 Fill Up Less, Drive More: The Complete Guide to Saving Fuel… • 06 Smooth Shifting: Navigating Common Transmission Problems an… • 07 P0013 B Camshaft Position - Actuator Circuit (Bank 1) • 08 8 Factors That Contribute to High Fuel Consumption • 09 What Happens When the Throttle Body Gets Dirty • 10 From Tires to Driveshafts: An Expert Explains Why Your Car … •

DTC codes / B01xx · Airbags, seats, doors, lights and comfort systems / B0120

B0120Passenger Pelvic/Thorax Airbag Deployment Control

B0120 indicates that the passenger pelvic/thorax airbag deployment control circuit has a fault, meaning the supplemental restraint system (SRS) computer has detected an abnormal condition in the circuit that fires the passenger's side airbag for pelvis and chest protection. The computer monitors the circuit's resistance and continuity and sets this code when the readings fall outside the expected range, which can prevent that airbag from deploying in a crash.

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

Symptoms you may notice

  • The airbag warning light on the instrument cluster stays illuminated after the bulb check.
  • A message such as 'Service Airbag' or 'SRS Fault' may appear on the driver information center.
  • The passenger-side airbag may be disabled, and some vehicles will show a passenger airbag off indicator even with an occupant present.
  • Often no symptoms besides the warning light, with the vehicle driving normally.
  • In rare cases, the passenger seatbelt pretensioner or side airbag may also be affected if the fault is in a shared circuit.

Common causes, most likely first

  1. A damaged or disconnected electrical connector under the passenger seat or at the airbag module.
  2. A chafed, pinched, or broken wire in the passenger airbag deployment circuit, often from seat movement or trim removal.
  3. A faulty passenger seat occupant detection sensor or weight sensor that shares the circuit.
  4. Corrosion or water intrusion in the connector or wiring harness, especially in vehicles with sunroof drains or leaky seals.
  5. A failed passenger pelvic/thorax airbag module itself, though this is less common than wiring issues.
  6. A defective SRS control module that is misreading the circuit resistance.
  7. Aftermarket accessories or previous repairs that tapped into the SRS wiring incorrectly.

How to diagnose and fix it

  1. Inspect the passenger seat area for loose connectors, damaged wiring, or signs of water intrusion, and reseat any connectors.
  2. Use a scan tool to read the SRS codes and live data for the passenger airbag circuit resistance and compare to specifications.
  3. Perform a resistance test on the passenger pelvic/thorax airbag squib circuit with a digital multimeter, following the manufacturer's procedure to avoid accidental deployment.
  4. Check the occupant detection system and seat weight sensor operation if the vehicle is equipped, as faults there can set this code.
  5. Inspect the SRS control module connectors and wiring for corrosion or damage, and verify power and ground to the module.
  6. If the circuit tests good, substitute a known-good airbag module or use a simulator to isolate the fault, following safety procedures.
  7. Clear the codes and verify the repair with a test drive and re-scan, ensuring the airbag light stays off.

Before you replace the passenger airbag

  • A common oversight is a disconnected or loose yellow SRS connector under the passenger seat after someone vacuums or adjusts the seat, which sets B0120 without any damaged parts.
  • The code can be set by a low battery or charging system issue that causes the SRS module to log a temporary circuit fault, so always check battery voltage and grounds first.
  • Do not probe airbag connectors with a powered test light or ordinary ohmmeter without following the service manual, as this can deploy the airbag or damage the module.
  • Aftermarket seat covers or heavy objects left on the passenger seat can interfere with the occupant detection system and trigger this code on some vehicles.
  • B0120 does not always mean the airbag itself is bad; the majority of cases trace to wiring or connectors, so replace the module only after thorough circuit testing.

Can I keep driving with B0120?

Because this code affects the passenger airbag's ability to deploy, the vehicle should not be considered safe for carrying a passenger in that seat until repaired. You can drive to a repair shop, but avoid collisions 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.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage