What Does B0079 Mean?
This code indicates the Body Control Module (BCM) or Restraint Control Module (RCM) has detected a subfault in the deployment control circuit for the driver's seatbelt pretensioner 'B'. The pretensioner is a pyrotechnic device that rapidly retracts the seatbelt during a collision to secure the occupant. A subfault suggests an electrical issue in the deployment circuit, such as high or low resistance, open circuit, short to ground, or internal control module communication error that prevents proper pretensioner deployment command.
Safety Warning
This is a critical safety issue as the driver's seatbelt pretensioner may not deploy properly during a collision, significantly reducing occupant protection and increasing injury risk. The vehicle should not be driven until repaired, as the supplemental restraint system is compromised.
Common Causes
35%
Damaged, corroded, or disconnected wiring harness and connector at the pretensioner or RCM, often from previous deployment, collision damage, or water intrusion
30%
Faulty seatbelt pretensioner assembly with internal circuit failure or degraded squib resistance
20%
Restraint Control Module (RCM) internal fault in deployment control circuit or driver output stage failure
10%
Clockspring or seat wiring issues affecting pretensioner circuit continuity
5%
Previous deployment not properly cleared or system not fully reset after collision repair
Diagnostic Steps
1
Step 1: Visually inspect the driver seatbelt pretensioner assembly and all visible wiring from the seat base to the B-pillar for signs of previous deployment (deployed pretensioners cannot be reused), physical damage, corrosion, chafing, or disconnected connectors. Check vehicle history for previous collisions.
2
Step 2: Using a digital multimeter, measure the resistance of the pretensioner squib circuit at the RCM connector (with pretensioner connected and RCM disconnected). Typical specification is 1.5-3.5 ohms; values outside this range or open/short circuit indicate pretensioner or wiring fault.
3
Step 3: Inspect and test continuity of all wiring between the pretensioner connector and RCM connector, checking for opens, shorts to ground, shorts to power, and resistance within 0.5 ohms. Pay special attention to connector terminals for corrosion, bent pins, or moisture.
4
Step 4: If wiring and pretensioner resistance are within specification, perform RCM self-test function using advanced scan tool to isolate internal module fault. Check for RCM software updates or technical service bulletins related to false deployment control faults.
5
Step 5: After repair (replacing pretensioner, wiring, or RCM), clear all codes from RCM memory, perform complete restraint system initialization procedure per manufacturer specifications, and road test to verify airbag warning light remains off and no codes return.
Estimated Repair Cost
$400 - $1,800
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) or Restraint Control Module (RCM) has detected a subfault in the deployment control circuit for the driver's seatbelt pretensioner 'B'. The pretensioner is a pyrotechnic device that rapidly retracts the seatbelt during a collision to secure the occup...
The most common cause of B0079 (Driver Seatbelt Pretensioner "B" Deployment Control (Subfault)) is: Damaged, corroded, or disconnected wiring harness and connector at the pretensioner or RCM, often from previous deployment, collision damage, or water intrusion
Typical repair costs for B0079 range from $400 to $1,800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is a critical safety issue as the driver's seatbelt pretensioner may not deploy properly during a collision, significantly reducing occupant protection and increasing injury risk. The vehicle should not be driven until repaired, as the supplemental restraint system is compromised.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B0079 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Supplemental Restraint System (SRS) / Airbag System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
