Engine-CodesLexus – B1861 Lexus

B1861 Lexus Code - Open in Driver Side Knee Airbag Squib Circuit

Quick Answer

The B1861 diagnostic trouble code for Lexus vehicles indicates an open circuit in the driver side knee airbag squib circuit. Common causes include Damaged wiring or connectors in the driver side knee airbag squib circuit, A faulty driver side knee airbag squib, Blown fuse related to the SRS system. 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
B1861 Lexus indicates Open in Driver Side Knee Airbag Squib Circuit.
Common causes
Common causes include Damaged wiring or connectors in the driver side knee airbag squib circuit, A faulty driver side knee airbag squib, Blown fuse related to the SRS system.
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.
Table of contents Created and updated by William Orellana on Sep 17, 2024
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Code B1861 Lexus Description

The B1861 diagnostic trouble code for Lexus vehicles indicates an open circuit in the driver side knee airbag squib circuit. The knee airbag squib is a component of the vehicle's supplemental restraint system (SRS) that is designed to deploy the knee airbag in the event of a collision. An open circuit in this circuit means that there is a break or discontinuity in the electrical connection, preventing the proper deployment of the knee airbag.

OBDII Code B1861 Lexus - Open in Driver Side Knee Airbag Squib Circuit
B1861 Lexus Code - Open in Driver Side Knee Airbag Squib Circuit

Common Causes of B1861 Lexus

  1. Damaged wiring or connectors in the driver side knee airbag squib circuit.
  2. A faulty driver side knee airbag squib.
  3. Blown fuse related to the SRS system.
  4. Malfunctioning SRS control module.
  5. Previous collision or impact that damaged the knee airbag system.

Symptoms of B1861 Lexus

  1. Illumination of the airbag warning light on the instrument panel.
  2. Inability to turn off the airbag warning light even after resetting the system.
  3. Diagnostic trouble code B1861 stored in the vehicle's computer system.
  4. Non-deployment of the driver side knee airbag during a crash.

How to Fix B1861 Lexus

  1. Begin by conducting a thorough visual inspection of the wiring and connectors in the driver side knee airbag squib circuit to check for any visible damage or corrosion.
  2. Use a multimeter to test the continuity of the wiring and connectors to identify any open circuits.
  3. If the wiring and connectors are in good condition, test the driver side knee airbag squib for proper functionality using a compatible diagnostic tool.
  4. Replace any damaged wiring, connectors, or the faulty knee airbag squib as needed.
  5. Clear the diagnostic trouble code from the vehicle's computer system and perform a test to ensure that the issue has been resolved.

Cost to Fix B1861 Lexus

The typical repair costs for addressing a B1861 diagnostic trouble code in a Lexus vehicle can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of parts for replacing damaged wiring, connectors, or a faulty knee airbag squib can range from $100 to $500. Labor costs at auto repair shops typically range from $80 to $150 per hour, with the total repair time varying based on the complexity of the issue.

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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 B1861 Lexus Code

1. What does the OBDII code B1861 mean on a Lexus?

The code B1861 indicates an open circuit in the driver-side knee airbag squib, which is part of the airbag deployment system.

2. What are the common symptoms of the B1861 code?

The airbag warning light will illuminate on the dashboard, and the driver-side knee airbag may not function properly during a collision.

3. What causes the B1861 code in a Lexus?

Common causes include damaged wiring, a disconnected or loose connector, a faulty knee airbag squib, or a malfunctioning airbag control module.

4. Is it safe to drive with the B1861 code on my Lexus?

Driving with this code is not recommended, as it indicates a potential malfunction in the airbag system, which could compromise safety in an accident.

5. How can I diagnose the B1861 code?

Diagnose the code by inspecting the wiring and connectors for damage or disconnection and using a scan tool to verify circuit continuity and resistance in the knee airbag squib.

6. Can I reset the B1861 code without fixing the problem?

Resetting the code without addressing the underlying issue will likely cause the code to reappear, as the fault in the circuit remains unresolved.

7. What repairs can fix the B1861 code?

Repairs may include reconnecting loose connectors, repairing or replacing damaged wiring, replacing the driver-side knee airbag squib, or servicing the airbag control module.

8. How much does it cost to fix the B1861 code on a Lexus?

The cost depends on the specific issue but can range from $100 for wiring repairs to $1,000 or more if the airbag module or squib needs replacement.

9. Can I fix the B1861 code myself?

If you have experience with automotive electronics and access to proper tools, you can attempt basic repairs like checking connectors and wiring. However, airbag systems are sensitive and may require professional service.

10. Does the B1861 code always mean the airbag squib is faulty?

No, the code can also be triggered by issues in the wiring, connectors, or airbag control module, so a thorough diagnosis is essential.

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