B0072 – Second Row Left Seat Belt Pretensioner Deployment Loop Circuit Fault

DTC B0072 indicates that the Supplemental Restraint System (SRS) has detected a fault in the second-row left seat belt pretensioner deployment loop circuit. Depending on the vehicle manufacturer, the fault may be caused by an open circuit, short to ground, short to battery voltage, or excessive resistance in the deployment loop.

Important: The exact definition of B0072 varies by manufacturer. Always consult the factory service manual for the correct diagnostic procedure.

Symptoms

• Airbag (SRS) warning light ON.
• Rear left seat belt pretensioner disabled.
• Stored B0072 code in the SRS module.
• Additional airbag system DTCs may be present.

Possible Causes

• Faulty second-row left seat belt pretensioner.
• Damaged or pinched wiring harness.
• Loose or corroded connector.
• Open circuit.
• Short to ground or battery voltage.
• Faulty SRS control module.

Typical Signal Flow Diagram

        +12V Battery
             │
        Ignition ON
             │
      ┌──────────────┐
      │  SRS Module  │
      └──────┬───────┘
             │
     Deployment Loop
             │
 ┌─────────────────────────────┐
 │ Rear Left Seat Belt         │
 │ Pretensioner Assembly       │
 └────────────┬────────────────┘
              │
         Return Circuit
              │
          SRS Module

Note: Connector locations, wire colors, and resistance values vary between manufacturers. Always use the correct wiring diagram for the specific vehicle.

Diagnostic Procedure

1. Scan the SRS module for all stored trouble codes.
2. Inspect the rear left seat belt pretensioner connector.
3. Check the wiring harness for damage or crushed wires.
4. Inspect terminals for corrosion or loose connections.
5. Perform continuity and resistance tests according to the manufacturer's repair manual.
6. Repair damaged wiring or replace defective components.
7. Clear the DTC and verify proper SRS operation.

Recommended Repairs

• Repair damaged wiring.
• Replace corroded connectors.
• Replace the rear left seat belt pretensioner if defective.
• Repair open or shorted circuits.
• Replace the SRS module only after confirming all other components are functioning correctly.

Safety Warning

Disconnect the negative battery terminal and wait at least 10–15 minutes before servicing any SRS component. Never test a pretensioner directly with a standard multimeter unless specified by the vehicle manufacturer.

Related DTC Codes

• B0070
• B0071
• B0073
• B0074
• B0080

Frequently Asked Questions (FAQ)

What does B0072 mean?

B0072 indicates a fault in the second-row left seat belt pretensioner deployment loop circuit.

Can I continue driving with B0072?

Yes, but the rear left seat belt pretensioner may not operate correctly during a collision.

What usually causes B0072?

The most common causes are damaged wiring, poor connector contact, or a faulty rear left seat belt pretensioner.

Will clearing the code repair the problem?

No. If the electrical fault remains, the SRS module will detect it again and the code will return.