B0079 OBD2 Code Guide
B0079 is a body / srs diagnostic trouble code. Use this hub to understand the plain meaning, the first checks to run, and which vehicle-specific guides may be more useful before replacing parts.
Driver Seatbelt Pretensioner
Code B0079 signifies a malfunction within the driver's side seatbelt pretensioner circuit. This is a critical safety system component, part of the Supplemental Restraint System (SRS), designed to rapidly tighten the seatbelt during a collision to secure the occupant more effectively. A B0079 code indicates that the SRS control module (often referred to as the Airbag Control Module or ACM) has detected an electrical fault, such as an open circuit, short circuit, or incorrect resistance, within the pretensioner's wiring or the pretensioner unit itself. This fault will typically illuminate the SRS warning light on the dashboard, indicating that the airbag system, including the pretensioners, may be disabled or not function as intended in an accident. Given its direct impact on occupant safety, immediate diagnosis and repair are paramount.
Code verification standard
B0079 is published with SAE J2012 / ISO 15031-6 code structure plus OBD2 B0079 diagnostic context.
First checks
- - Read all stored and pending codes before clearing anything.
- - Save freeze-frame data so you know speed, load and temperature when the code set.
- - Inspect wiring, connectors, fuses, hoses and obvious leaks tied to the named system.
- - Compare live data against realistic values before buying sensors or modules.
- - Clear the code only after repair and complete a drive cycle to confirm it does not return.
B0079 diagnostic path
- 1Scan for SRS Codes and Data: Use an advanced OBD2 scanner capable of communicating with the SRS module. Read all stored and pending SRS codes. Note any additional codes that might be present, as they could indicate a broader system issue or provide context for B0079. Check live data for the driver's seatbelt pretensioner circuit, if available, looking for resistance values or circuit status.
- 2Visual Inspection of Wiring and Connectors: Disconnect the vehicle's battery (wait at least 10-15 minutes after disconnection to allow SRS capacitors to discharge). Carefully inspect the wiring harness leading to the driver's seatbelt pretensioner for any signs of damage, fraying, pinching, or corrosion. Pay close attention to the connector at the pretensioner itself and any inline connectors under the seat or along the pillar. Ensure all connections are secure and free of debris or corrosion.
- 3Resistance Check of Pretensioner Circuit: With the battery disconnected and the pretensioner connector unplugged, use a multimeter to measure the resistance across the two terminals of the driver's seatbelt pretensioner unit. Compare this reading to the manufacturer's specifications (typically found in a service manual). An open circuit (infinite resistance) or a short circuit (near zero resistance) indicates a faulty pretensioner. Never apply power directly to the pretensioner or use an ohmmeter on a live circuit, as this can cause accidental deployment.
- 4Wiring Integrity Test: With the battery still disconnected and the pretensioner unplugged, test the continuity and resistance of the wiring harness from the SRS module connector to the pretensioner connector. Check for continuity between each wire and ground, and between the two wires themselves, to rule out shorts. Also, measure the resistance of each wire to ensure it's within specifications (typically very low, near 0 ohms). Repair any open circuits, shorts, or high resistance in the wiring.
- 5Verify Repair and Clear Codes: Once repairs are made, reconnect the battery. Use the scan tool to clear all SRS codes. Start the vehicle and observe the SRS warning light. If the light remains off, perform a test drive to ensure the code does not return. If the light reappears, re-evaluate the diagnosis, potentially considering a faulty SRS module as a last resort after confirming all other components and wiring are sound.
Verify before repair
- - Repair or replace damaged wiring and connectors leading to the driver's seatbelt pretensioner.
- - Replace the faulty driver's seatbelt pretensioner unit.
- - Clean corroded electrical contacts at the pretensioner and SRS module connectors.
- - (Less common) Replace the SRS (Airbag) control module if all other components and wiring are confirmed good.
Vehicle-specific pages to check next
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