B1921 Code - Air Bag Diagnostic Monitor Ground Circuit Open

Quick Answer

The B1921 diagnostic trouble code (DTC) refers to an issue with the airbag system's diagnostic monitor ground circuit being open. Common causes include Loose or corroded ground connection, Faulty airbag diagnostic monitor, Wiring harness issues. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means

B1921 indicates Air Bag Diagnostic Monitor Ground Circuit Open.

Common causes

Common causes include Loose or corroded ground connection, Faulty airbag diagnostic monitor, Wiring harness issues.

Severity

High - diagnose this code as soon as possible.

Can I drive?

Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

• Description
• Common Causes
• Symptoms
• How To Fix
• Cost to Fix
• FAQs
• Comments
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Common Causes of B1921

Symptoms of B1921

How to Fix B1921

Cost to Fix B1921

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Code B1921 Information for Specific Makes

• B1921 Ford — RCM Bracket Ground Resistance High
• B1921 Jaguar — RCM Bracket Ground Resistance High
• B1921 Lexus — Open In Rear Pretensioner Squib RH Circuit
• B1921 Lincoln — RCM Bracket Ground Resistance High
• B1921 Mercury — RCM Bracket Ground Resistance High
• B1921 Scion — Open In Rear Pretensioner Squib RH Circuit
• B1921 Toyota — Open In Rear Pretensioner Squib RH Circuit

Precautions for SRS “AIR BAG” and “SEAT BELT PRE-TENSIONER” Service

• Never probe the electrical connectors on air bag, side air curtain modules or seat belts.
• Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors.
• Do not use electrical test equipment to check SRS circuits unless instructed to in this Service Manual.
• Before servicing the SRS, turn ignition switch OFF, disconnect both battery cables and wait at least 3 minutes. For approximately 3 minutes after the cables are removed, it is still possible for the air bag and seat belt pre-tensioner to deploy. Therefore, do not work on any SRS connectors or wires until at least 3 minutes have passed.

Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B1921 Code

1. What are common symptoms of OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open)?

- Common symptoms include the airbag warning light staying illuminated on the dashboard and potential non-deployment of the airbags in case of an accident.

2. What causes the OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open) to trigger?

- This code is typically triggered by a break or open circuit in the ground wire of the airbag diagnostic monitor system.

3. How serious is OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open)?

- This code is considered serious as it affects the proper functioning of the airbag system, potentially compromising passenger safety in the event of a collision.

4. Can I continue driving with OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open) present?

- It is not recommended to drive with this code present as it may lead to the airbags not deploying properly in case of an accident.

5. How can I diagnose the issue causing OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open)?

- Diagnosing this issue typically involves inspecting the wiring and connectors related to the airbag diagnostic monitor system for any breaks or damage.

6. What are the repair options for OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open)?

- Repair options may include repairing or replacing the damaged ground wire in the airbag diagnostic monitor system and clearing the diagnostic trouble codes.

7. Can I reset OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open) without fixing the underlying issue?

- While you can clear the code temporarily, it is crucial to address the root cause to ensure the proper functioning of the airbag system.

8. Are there any safety precautions I should take when working on OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open)?

- When working on the airbag system, it is essential to disconnect the vehicle's battery and wait for a few minutes to discharge any residual power to prevent accidental airbag deployment.

9. How much does it cost to repair OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open)?

- The cost of repair can vary depending on the extent of the damage and whether you choose to fix it yourself or have a professional technician address the issue.

10. Can OBDII code B1921 (Air Bag Diagnostic Monitor Ground Circuit Open) be a recurring problem?

- If the underlying issue causing the code is not properly addressed, it can lead to a recurring problem with the airbag diagnostic monitor system.