B3857 Code - Incorrect Rollover Sensor Installed

Quick Answer

The diagnostic code B3857 indicates that an incorrect rollover sensor has been installed in the vehicle. Common causes include Incorrect installation of a replacement rollover sensor during a repair or maintenance service, Use of aftermarket or incompatible rollover sensors, Faulty wiring or connections to the rollover sensor. 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

B3857 indicates Incorrect Rollover Sensor Installed.

Common causes

Common causes include Incorrect installation of a replacement rollover sensor during a repair or maintenance service, Use of aftermarket or incompatible rollover sensors, Faulty wiring or connections to the rollover sensor.

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
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Common Causes of B3857

Symptoms of B3857

How to Fix B3857

Cost to Fix B3857

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Code B3857 Information for Specific Makes

• B3857 Buick — Headlamp High Beam Signal Circuit
• B3857 Cadillac — Headlamp High Beam Signal Circuit
• B3857 Chevrolet — Incorrect Rollover Sensor Installed
• B3857 GMC — Incorrect Rollover Sensor Installed
• B3857 Hummer — Incorrect Rollover Sensor Installed
• B3857 Pontiac — Incorrect Rollover Sensor Installed
• B3857 Saturn — Incorrect Rollover Sensor Installed

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 B3857 Code

1. What are the common symptoms of OBDII code B3857 (Incorrect Rollover Sensor Installed)?

- Common symptoms include the airbag warning light being illuminated on the dashboard and potential issues with the vehicle's airbag system.

2. What can cause OBDII code B3857 to trigger?

- OBDII code B3857 is triggered when the rollover sensor installed in the vehicle does not match the specifications required by the vehicle's system.

3. How serious is the OBDII code B3857 (Incorrect Rollover Sensor Installed)?

- This code is considered serious as it indicates a potential malfunction in the vehicle's safety system, particularly the airbag deployment in the event of a rollover.

4. What should I do if I encounter OBDII code B3857?

- It is recommended to have the vehicle inspected by a qualified mechanic to diagnose the issue with the rollover sensor and ensure proper functioning of the airbag system.

5. Can I continue driving my vehicle with OBDII code B3857 present?

- It is not recommended to continue driving the vehicle with this code active, as it may compromise the effectiveness of the airbag system in the event of an accident.

6. How is OBDII code B3857 diagnosed?

- Diagnosis typically involves using a diagnostic scanner to read the code, followed by a thorough inspection of the rollover sensor and related components.

7. What is the typical repair for OBDII code B3857?

- The typical repair involves replacing the incorrect rollover sensor with the appropriate one specified for the vehicle.

8. Can I reset OBDII code B3857 without fixing the underlying issue?

- While you can clear the code with a diagnostic tool, it is crucial to address the underlying problem to ensure the proper functioning of the airbag system.

9. Are there any DIY repair tips for OBDII code B3857?

- DIY repair is not recommended for this code, as it involves working with critical safety components. It is best to have a professional mechanic handle the repair.

10. How can I prevent OBDII code B3857 from occurring in the future?

- To prevent this code from occurring, ensure that any replacement sensors or components installed in the vehicle meet the manufacturer's specifications for compatibility and functionality.