Definition of check engine code B0020


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When it comes to the smooth operation of our vehicles, modern automobiles are equipped with an array of advanced sensors and control systems to ensure optimal performance and safety. However, these systems occasionally encounter issues that can trigger a check engine light, indicating a problem. One such issue is the check engine code B0020. In this comprehensive guide, we’ll delve into the definition of check engine code B0020, its potential causes, symptoms, and step-by-step solutions to effectively address this automotive concern.

Definition of check engine code B0020

Generic (Common for all car manufacturers)

Left Side Airbag Deployment Control (Subfault)
B Body Code
Problem is antilock brake system, electronic suspension and steering systems.
0 SAE - Generic
0 Accelerator Pedal Position (APP) Sensor 1 Performance
2 BBV Sensor Circuit Low Voltage
0 Park/Neutral Postion (PNP) Switch Circuit Engine Torque Signal Circuit

Check engine code B0020 is a diagnostic trouble code (DTC) that is typically related to the Supplemental Restraint System (SRS), commonly known as the airbag system, in a vehicle. This code specifically points to a problem with the occupant classification system. The occupant classification system is responsible for detecting the presence and position of passengers in the front passenger seat and determining whether to deploy the airbag during a collision. When the system detects an issue that affects its proper function, it triggers the check engine light and stores the B0020 code.

Symptoms of Check Engine Code B0020

Vehicles experiencing issues related to check engine code B0020 may exhibit several noticeable symptoms, including:

  • Illuminated Airbag Light: One of the most common signs is the illumination of the airbag warning light on the vehicle’s dashboard.
  • Inoperative Airbag System: The airbag system might become inoperative due to the faulty occupant classification system, potentially compromising passenger safety in the event of a collision.
  • Diagnostic Trouble Codes: Modern vehicles are equipped with onboard diagnostic systems that store trouble codes when a malfunction is detected. Alongside the B0020 code, other related codes might also be stored.

Common Causes of Check Engine Code B0020

Several factors can contribute to the occurrence of check engine code B0020. These include:

  • Faulty Occupant Classification Sensor: The occupant classification sensor may fail to accurately detect passengers’ presence or position, leading to the B0020 code.
  • Damaged Wiring or Connectors: Physical damage or corrosion in the wiring harness or connectors associated with the occupant classification system can disrupt its proper function.
  • Software or Calibration Issues: Sometimes, the software or calibration of the occupant classification system might become corrupted or outdated, triggering the code.

How to Diagnose Check Engine Code B0020

Diagnosing check engine code B0020 requires a systematic approach to identify the root cause accurately. Here’s a step-by-step guide:

  1. Retrieve Diagnostic Trouble Codes: Use an OBD-II scanner to retrieve the stored trouble codes, including B0020, along with any other related codes.
  2. Visual Inspection: Inspect the wiring, connectors, and components associated with the occupant classification system for visible damage or corrosion.
  3. Occupant Classification Sensor Testing: Test the occupant classification sensor using a multimeter or specialized diagnostic tools to ensure it’s functioning correctly.
  4. Software Update or Calibration: Check for available software updates or recalibration procedures provided by the vehicle manufacturer to address software-related issues.

Fixing Check Engine Code B0020: Solutions and Repairs

Depending on the diagnosis, there are several potential solutions to address check engine code B0020:

  • Sensor Replacement: If the occupant classification sensor is found to be faulty, replacing it with a new, OEM-quality sensor is recommended.
  • Wiring Repair: In cases of damaged wiring or connectors, repairing or replacing the affected components is necessary.
  • Software Update: If the issue is related to software, performing a software update or recalibration as per the manufacturer’s instructions can rectify the problem.


Understanding the definition of check engine code B0020 is crucial for maintaining the safety and functionality of your vehicle’s airbag system. By identifying the causes, symptoms, and appropriate solutions for this issue, you can ensure that your car’s occupants are well-protected during unexpected situations. Remember, while some diagnostics and repairs can be done at home, consulting a professional mechanic is always a wise choice when dealing with complex automotive problems.


What does check engine code B0020 mean?

Definition of check engine code B0020

Check engine code B0020 indicates a problem with the occupant classification system in a vehicle’s airbag system. It points to issues with accurately detecting passengers’ presence and position in the front passenger seat.

Can I continue driving with check engine code B0020?

While the vehicle might still be drivable with the check engine code B0020 illuminated, it’s crucial to address the issue promptly. A malfunctioning occupant classification system can compromise passenger safety in the event of a collision.

How do I reset the check engine light after fixing code B0020?

After resolving the issue causing check engine code B0020, you can reset the check engine light using an OBD-II scanner or by disconnecting the vehicle’s battery for a few minutes.

Is it possible to diagnose and fix B0020 at home?

Diagnosing and fixing check engine code B0020 at home is possible if you have the necessary tools, technical knowledge, and access to accurate diagnostic information. However, for complex issues, it’s advisable to consult a professional mechanic.

What is the approximate cost of repairing B0020?

The cost of repairing check engine code B0020 can vary based on factors like the cause of the issue, the vehicle’s make and model, and labor costs in your area. It’s recommended to obtain quotes from reputable repair shops.

Can a faulty airbag system lead to the B0020 code?

Yes, a faulty airbag system, particularly issues related to the occupant classification system, can trigger the B0020 code. Proper diagnosis is essential to determine the exact cause.

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