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Engine-Codes – Nissan – B142B Nissan

B142B Nissan Code - Ignition Voltage

Quick Answer

The diagnostic code B142B refers to an issue with the ignition voltage supplied to the Airbag Diagnosis Sensor Unit, which is critical for the proper functioning of the airbag system in a vehicle. Common causes include Faulty Airbag Diagnosis Sensor Unit, Open or shorted harness in the Airbag Diagnosis Sensor Unit, Poor electrical connection in the Airbag Diagnosis Sensor Unit 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
B142B Nissan indicates Ignition Voltage.
Common causes
Common causes include Faulty Airbag Diagnosis Sensor Unit, Open or shorted harness in the Airbag Diagnosis Sensor Unit, Poor electrical connection in the Airbag Diagnosis Sensor Unit 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 Nov 10, 2025
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Code B142B Nissan Description

The diagnostic code B142B refers to an issue with the ignition voltage supplied to the Airbag Diagnosis Sensor Unit, which is critical for the proper functioning of the airbag system in a vehicle. This unit, often referred to as the Airbag Control Module or Electronic Crash Unit, plays a vital role in monitoring collision sensors and determining when to deploy airbags in the event of a crash. When the ignition is turned to the ON position, the Airbag Diagnosis Sensor Unit receives power, allowing it to perform its functions. If the unit detects either low or high ignition voltage, it triggers the B142B code. Ignoring this code can lead to serious long-term effects, including the potential failure of the airbag system to deploy during an accident, which significantly increases the risk of injury to occupants. Additionally, the presence of a malfunctioning airbag system can lead to increased insurance premiums and may cause the vehicle to fail safety inspections. The underlying mechanics involve the electrical connections and circuits that supply power to the airbag system, which must be in optimal condition for the airbags to function correctly. If there are issues with voltage levels, it can indicate problems with the battery, wiring, or the airbag control module itself.
OBDII Code B142B Nissan - Ignition Voltage
B142B Nissan Code - Ignition Voltage

Common Causes of B142B Nissan

  1. Faulty Airbag Diagnosis Sensor Unit
  2. Open or shorted harness in the Airbag Diagnosis Sensor Unit
  3. Poor electrical connection in the Airbag Diagnosis Sensor Unit circuit
  4. Battery voltage issues affecting the airbag system
  5. Corrosion or damage in wiring related to the airbag system

Symptoms of B142B Nissan

  1. Air Bag Warning Light ON
  2. Engine Light ON (or Service Engine Soon Warning Light)
  3. Intermittent airbag system functionality
  4. Diagnostic trouble codes related to airbag system
  5. Potential failure of airbags to deploy in a crash

How to Fix B142B Nissan

  1. Perform a thorough inspection of the Airbag Diagnosis Sensor Unit and its connections.
  2. Check for any open or shorted circuits in the wiring harness associated with the airbag system.
  3. Test the Airbag Diagnosis Sensor Unit for proper functionality and replace if faulty.
  4. Inspect the vehicle's battery and charging system to ensure proper voltage levels.
  5. Clear the diagnostic trouble codes and conduct a test drive to confirm the issue is resolved.

Cost to Fix B142B Nissan

The cost to diagnose and repair issues related to the B142B code typically ranges from $150 to $600, depending on the specific cause and required repairs. This estimate includes parts and labor, with labor rates generally falling between $80 and $150 per hour. Dealerships may charge higher rates, while independent shops may offer more competitive pricing. The final cost can vary based on the vehicle's make and model, as well as the location of the repair shop.

Need more information about the B142B Nissan 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.

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