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Engine-Codes – Generic – B1904

B1904 Code - Air Bag Crash Sensor 2 Feed/Return Circuit Failure

Quick Answer

The B1904 diagnostic trouble code indicates a failure in the airbag crash sensor 2 feed/return circuit. Common causes include Faulty crash sensor feed/return circuit, Damaged wiring or connectors in the airbag system, Corrosion or moisture intrusion in the sensor circuit. 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
B1904 indicates Air Bag Crash Sensor 2 Feed/Return Circuit Failure.
Common causes
Common causes include Faulty crash sensor feed/return circuit, Damaged wiring or connectors in the airbag system, Corrosion or moisture intrusion in the sensor circuit.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 05, 2024
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Code B1904 Description

The B1904 diagnostic trouble code indicates a failure in the airbag crash sensor 2 feed/return circuit. This sensor is a crucial component of the vehicle's airbag system, responsible for detecting sudden deceleration during a crash and deploying the airbags to protect the occupants. When this circuit fails, it can compromise the functionality of the airbag system, potentially leading to the airbags not deploying in the event of a crash. This poses a significant safety risk to the vehicle's occupants and should be addressed promptly.

OBDII Code B1904 - Air Bag Crash Sensor 2 Feed/Return Circuit Failure
B1904 Code - Air Bag Crash Sensor 2 Feed/Return Circuit Failure

Common Causes of B1904

  1. Faulty crash sensor feed/return circuit
  2. Damaged wiring or connectors in the airbag system
  3. Corrosion or moisture intrusion in the sensor circuit
  4. Impact or damage to the crash sensor itself
  5. Electrical issues in the vehicle's system

Symptoms of B1904

  1. Airbag warning light illuminated on the dashboard
  2. Inability to reset the airbag warning light
  3. Airbags not deploying during a crash
  4. SRS (Supplemental Restraint System) warning message displayed on the instrument panel
  5. Loss of communication with the airbag module

How to Fix B1904

  1. Diagnose the specific cause of the circuit failure using a diagnostic scanner
  2. Inspect the wiring and connectors for any damage or corrosion
  3. Repair or replace any damaged wiring or connectors
  4. Test the circuit to ensure proper functionality
  5. Clear the diagnostic trouble codes and reset the airbag system

Cost to Fix B1904

The cost of repairing an airbag crash sensor 2 feed/return circuit failure can vary depending on the extent of the damage and the specific components that need to be replaced. On average, the repair costs for this issue can range from $200 to $500, including parts and labor. However, it's important to note that labor rates at auto repair shops can vary, so it's recommended to check with local shops for a more accurate estimate. Additionally, if the issue is not addressed promptly, it could lead to more severe damage to the vehicle's airbag system, resulting in higher repair costs in the long run.

Need more information about the B1904 code?

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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 B1904 Code

1. What are the common symptoms of OBDII code B1904 (Air Bag Crash Sensor 2 Feed/Return Circuit Failure)?

The common symptoms of this code may include the airbag warning light illuminating on the dashboard, the airbags may not deploy in the event of a crash, and diagnostic trouble codes related to the airbag system may be stored.

2. What can cause OBDII code B1904 to trigger?

This code is typically triggered by a malfunction in the air bag crash sensor 2 feed/return circuit, which can be caused by wiring issues, a faulty sensor, or a poor connection in the circuit.

3. How serious is OBDII code B1904?

OBDII code B1904 is a serious issue as it indicates a failure in the air bag crash sensor circuit. If this code is present, it is crucial to address the issue promptly to ensure the airbag system functions properly in the event of a collision.

4. How can I diagnose OBDII code B1904?

Diagnosing this code usually involves using a scan tool to retrieve the specific code, inspecting the wiring and connections related to the air bag crash sensor 2, and testing the sensor itself for proper functionality.

5. Can I drive with OBDII code B1904 present?

It is not recommended to drive with OBDII code B1904 present because it indicates a potential issue with the airbag system, which is a crucial safety feature in your vehicle. It is best to address the problem as soon as possible.

6. How can I repair OBDII code B1904?

Repairing this code involves identifying the root cause of the issue, which may be a faulty sensor, damaged wiring, or a poor connection. Once identified, the necessary repairs or replacements can be made to resolve the problem.

7. Are there any DIY tips for fixing OBDII code B1904?

While it is possible to diagnose the code yourself, repairing OBDII code B1904 may require specialized tools and expertise. It is recommended to seek the assistance of a professional mechanic to ensure the issue is properly addressed.

8. How much does it cost to fix OBDII code B1904?

The cost of fixing OBDII code B1904 can vary depending on the root cause of the issue, the extent of the repairs needed, and the labor rates in your area. It is advisable to obtain quotes from different repair shops to compare prices.

9. Can resetting the OBDII system clear code B1904?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue causing OBDII code B1904 is not addressed, the code is likely to return. It is important to diagnose and fix the root cause of the problem.

10. Is OBDII code B1904 a common issue in vehicles?

While not as common as some other OBDII codes, B1904 can occur in vehicles with airbag crash sensor systems. Proper maintenance and care of the airbag system can help prevent this code from triggering.

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