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B3902 Buick Code - Incorrect Immobilizer Identifier Received

Quick Answer

When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. Common causes include Faulty Body Control Module (BCM), Body Control Module harness is open or shorted, Body Control Module circuit poor electrical connection. 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
B3902 Buick indicates Incorrect Immobilizer Identifier Received.
Common causes
Common causes include Faulty Body Control Module (BCM), Body Control Module harness is open or shorted, Body Control Module circuit poor electrical connection.
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.
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Code Popularity 4,326
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Jun 16, 2023
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Code B3902 Buick Description

When certain modules are programmed and configured during installation, the module learns a specific environment identifier which is unique to the vehicle. The environment identifier is used to prevent the swapping modules between vehicles. The Body Control Module (BCM) is the keeper of the environment identifier. The instrument cluster, electronic brake control module, HVAC control module, inflatable restraint sensing and diagnostic module, Engine Control Module (ECM), and steering column lock module (if equipped) each learn the environment identifier during their configuration process. During vehicle operation, the BCM sends the immobilizer identifier as a challenge and each module responds to the challenge by sending the environment identifier back to the BCM. If the BCM sends an incorrect immobilizer identifier or a specific number of incorrect environment identifiers are received, vehicle starting is disabled. The Diagnostic Trouble Code (DTC) sets when the control module's environment identifier does not match the environment identifier stored by the BCM.
OBDII Code B3902 Buick - Incorrect Immobilizer Identifier Received - AutoCodes.com
B3902 Buick Code - Incorrect Immobilizer Identifier Received
What does this mean?

What are the Possible Causes of the DTC B3902 Buick?

  • Faulty Body Control Module (BCM)
  • Body Control Module harness is open or shorted
  • Body Control Module circuit poor electrical connection

How to Fix the DTC B3902 Buick?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3902 Buick code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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 B3902 Buick Code

1. What does OBDII code B3902 mean on a Buick?

Code B3902 indicates that the vehicle's immobilizer system has detected an incorrect or unrecognized identifier, preventing the vehicle from starting.

2. What are the common symptoms of code B3902 in a Buick?

Symptoms include the engine failing to start, the security or anti-theft light staying illuminated or flashing, and possibly a "no crank" condition.

3. What causes code B3902 in a Buick?

Common causes include a faulty key fob, a damaged immobilizer antenna, a malfunctioning body control module (BCM), or a programming issue with the key or immobilizer.

4. Can a low key fob battery cause code B3902?

Yes, a low or dead key fob battery can prevent the key's identifier from being properly transmitted, triggering code B3902.

5. How is code B3902 diagnosed on a Buick?

A technician will typically use a scan tool to verify the code, check the key fob signal, inspect the immobilizer system components, and test the BCM for proper functionality.

6. Can I fix code B3902 myself?

If the issue is a low key fob battery, replacing the battery may resolve it. For more complex issues, such as immobilizer or BCM faults, professional repair is recommended.

7. Does code B3902 mean my key needs reprogramming?

Possibly. If the key or immobilizer system has lost synchronization, reprogramming the key or resetting the immobilizer may be required.

8. How much does it cost to fix code B3902 in a Buick?

Repair costs can vary widely, from $20–$50 for a new key fob battery to $200–$500 or more for immobilizer or BCM repairs.

9. Can a bad BCM cause code B3902 in a Buick?

Yes, a malfunctioning Body Control Module can fail to properly communicate with the immobilizer system, causing this code.

10. Is it safe to drive with code B3902 active?

No, the vehicle may not start at all with this code active, so it needs to be resolved before the car can be driven.

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