B0020 – Driver Frontal Deployment Loop (Stage 2) Open indicates that the Supplemental Restraint System (SRS) control module has detected an open circuit in the second-stage firing loop of the driver’s frontal airbag. Stage 2 is the additional igniter responsible for full-force deployment during more severe crashes. When this loop is open, the airbag may not deploy at the correct force or may be disabled entirely. This guide explains what B0020 means, the symptoms to expect, the most common causes, how to diagnose it safely, and the best repair solutions.
What Does B0020 Mean?
B0020 is a body-system OBD-II code that appears when the SRS module detects that the Stage 2 driver-airbag deployment loop has no electrical continuity — meaning the circuit is “open.” This can be caused by disconnected connectors, broken wiring, a failed clockspring, or an open igniter inside the airbag module.
Since Stage 2 assists with higher-force deployment, the SRS unit disables that stage to prevent unsafe behavior. The airbag warning light remains illuminated until the problem is repaired. Some vehicles may still deploy Stage 1, but others disable the entire driver airbag as a precaution.
Quick Reference
- OBD-II Family: B-Code (Body)
- Scope: Generic
- System: SRS – Driver Frontal Airbag (Stage 2)
- Difficulty Level: Moderate–Advanced
- Estimated Repair Cost: €90–€650+
- Last Updated: 27 November 2025
Real-World Example / Field Notes
A coupe arrived with the airbag light on after steering-wheel replacement. B0020 was stored. The technician found the Stage 2 connector tucked behind the wheel, never reconnected after installation. Reattaching the connector and clearing the code immediately restored the SRS system.
Another case involved a high-mileage sedan where the airbag light came on intermittently while turning. Testing revealed a failing clockspring with a broken Stage 2 circuit track. Replacing the clockspring resolved B0020 and restored full driver-airbag readiness.
Symptoms of B0020 – Driver Frontal Deployment Loop (Stage 2) Open
- Airbag light illuminated: Indicates a disabled or impaired airbag stage.
- Stage 2 deployment disabled: Airbag may deploy weakly or not at all in severe crashes.
- Intermittent SRS light: Often changes when turning the wheel or hitting bumps.
- Other SRS codes present: Frequently accompanies clockspring or connector issues.
- Warning after steering-wheel or dash work: Indicates connectors were disturbed.
Common Causes of B0020
Most Common Causes
- Disconnected or loose Stage 2 airbag connector
- Failed clockspring (open internal circuit)
- Broken or damaged wiring in the steering column
- Open igniter inside the driver airbag module (Stage 2)
- Incorrect reconnection during steering-wheel installation
Less Common Causes
- SRS control module internal failure
- Connector corrosion from moisture or spills
- Aftermarket steering wheels or buttons interfering with wiring
- Physical damage to airbag module during repairs
- Low voltage affecting SRS resistance readings (rare)
Diagnosis: Step-by-Step Guide
B0020 involves an open airbag-deployment circuit, so all testing must follow SRS-safe procedures.
Tools You’ll Need
SRS-capable scan tool, multimeter with airbag-safe adapters, wiring diagrams, torx/steering-wheel tools, trim tools, and insulated gloves.
- Disconnect the battery: Wait the specified time before handling SRS components.
- Scan all SRS codes: Confirm B0020 and note related loop or clockspring faults.
- Inspect driver-airbag connectors: Ensure Stage 2 connector is fully locked, clean, and dry.
- Check the clockspring: Stage 2 circuits often fail due to broken internal ribbon tracks.
- Measure Stage 2 circuit continuity: Use only airbag-approved testing tools.
- Check steering-column wiring: Look for pinch points, cuts, or broken insulation.
- Perform wiggle-test: With SRS disabled, watch for continuity changes as the wheel moves.
- Inspect the driver airbag module: Look for damage, previous collision repairs, or open igniter.
- Verify SRS module grounds and power: Poor grounding causes false loop readings.
- Replace or repair components as needed: Then clear codes and retest the system.
Pro Tip: If B0020 appears only when turning the steering wheel, the clockspring is almost always the cause.
Possible Fixes & Repair Costs
- Reconnect or clean airbag connectors: €20–€80
- Repair steering-column wiring: €40–€120
- Replace clockspring: €120–€350
- Replace driver airbag module: €200–€450+
- Replace SRS control module: €180–€350+
Can I Still Drive With B0020?
While the vehicle is drivable, it is not fully safe. The Stage 2 igniter for the driver airbag is disabled, meaning the airbag may not deploy with full force during a serious collision. On some vehicles, Stage 1 may still operate; on others, the entire airbag is disabled. Immediate repair is strongly recommended.
Related Codes
- B0019 – Occupant Restraint Airbag Circuit Fault
- B0018 – Body Circuit Fault — Restraint Sensor Signal
- B0017 – Body Circuit Signal Integrity Fault
- B0016 – Occupant Sensing Circuit Fault (SRS)
- B0014 – Occupant Restraint Circuit Fault
- B0011 – Occupant Restraint Circuit Fault
- B0009 – Restraint System Circuit Fault
- B0008 – Supplemental Restraint System Circuit High
- B0007 – Supplemental Restraint System Circuit Fault
- B0006 – Restraint Deployment Commanded Too Long
Key Takeaways
- B0020 indicates an open circuit in the Stage 2 driver-airbag deployment loop.
- Most issues involve loose connectors, broken wiring, or a failed clockspring.
- The driver airbag may deploy incorrectly or be fully disabled.
- Prompt SRS-safe diagnosis and repair are essential for occupant safety.
FAQ
Does B0020 disable the driver airbag?
Stage 2 is disabled; depending on the vehicle, Stage 1 may remain active or the entire airbag may be shut down.
Is the clockspring a common cause?
Yes. Stage 2 open-circuit faults frequently trace back to a broken clockspring ribbon cable.
Can I clear the code without fixing it?
No. The SRS module will not allow the airbag system to re-arm until the open circuit is repaired.
Is Stage 2 deployment important?
Yes. It provides additional force in higher-severity crashes, improving occupant protection.
Can low voltage trigger B0020?
Low voltage can cause false readings, but true B0020 faults almost always involve wiring or component failure.