B0071 – Passenger Seat Belt Pretensioner Deployment Loop Circuit Fault

DTC B0071 indicates that the Supplemental Restraint System (SRS) has detected a fault in the passenger seat belt pretensioner deployment loop circuit. 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 B0071 may vary between vehicle manufacturers. Always verify the code using the factory service information for the specific vehicle.

Symptoms

• SRS (Airbag) warning light illuminated.
• Passenger seat belt pretensioner disabled.
• One or more additional SRS DTCs stored.
• Reduced occupant protection during a collision.

Possible Causes

• Faulty passenger seat belt pretensioner.
• Open circuit in the pretensioner wiring.
• Short to ground or battery voltage.
• Loose, damaged, or corroded connector under the passenger seat.
• Damaged wiring harness.
• Faulty SRS control module.

Typical Signal Flow Diagram

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

Note: Wire colors, connector pinouts, and resistance specifications differ between manufacturers. Always use the appropriate wiring diagram for the vehicle being serviced.

Diagnostic Procedure

1. Read all stored SRS trouble codes with a professional scan tool.
2. Inspect the connector beneath the passenger seat.
3. Check the harness for broken, pinched, or stretched wires.
4. Inspect terminals for corrosion or poor contact.
5. Perform continuity and resistance tests following the manufacturer's repair manual.
6. Repair damaged wiring or replace faulty components.
7. Clear the DTC and verify proper SRS operation.

Recommended Repairs

• Repair damaged wiring harness.
• Replace loose or corroded connectors.
• Replace the passenger seat belt pretensioner if defective.
• Repair any open or shorted circuit.
• Replace or reprogram the SRS module only after confirming all other components are operating correctly.

Safety Warning

Disconnect the negative battery terminal and wait at least 10–15 minutes before servicing any SRS component. Never apply external voltage or directly measure an airbag or pretensioner igniter with a standard multimeter.

Related DTC Codes

• B0069
• B0070
• B0072
• B0073
• B0080

Frequently Asked Questions (FAQ)

What does B0071 mean?

B0071 indicates a fault in the passenger seat belt pretensioner deployment loop circuit.

Can I continue driving with B0071?

The vehicle may still operate normally, but the passenger seat belt pretensioner may not activate properly during a collision.

What is the most common cause?

The most common causes include damaged wiring under the passenger seat, poor connector contact, or a faulty pretensioner.

Will clearing the code fix the problem?

No. If the electrical fault has not been repaired, the SRS module will detect it again and store the code.