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B1B78 Mitsubishi Code - Passenger Seat Weight Sensor 3 Left Front Performance

Quick Answer

The B1B78 Mitsubishi code refers to an issue with the passenger seat weight sensor 3 in the left front seat of the vehicle. Common causes include Faulty passenger seat weight sensor, Wiring or connector issues in the sensor circuit, Corrosion or damage to the sensor components. 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
B1B78 Mitsubishi indicates Passenger Seat Weight Sensor 3 Left Front Performance.
Common causes
Common causes include Faulty passenger seat weight sensor, Wiring or connector issues in the sensor circuit, Corrosion or damage to the sensor components.
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 Sep 12, 2024
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Code B1B78 Mitsubishi Description

The B1B78 Mitsubishi code refers to an issue with the passenger seat weight sensor 3 in the left front seat of the vehicle. This sensor is responsible for detecting the weight of the passenger sitting in the seat and activating the airbag system accordingly. When this sensor fails to perform correctly, it can affect the deployment of the airbag in case of an accident, compromising the safety of the passenger.

OBDII Code B1B78 Mitsubishi - Passenger Seat Weight Sensor 3 Left Front Performance
B1B78 Mitsubishi Code - Passenger Seat Weight Sensor 3 Left Front Performance

Common Causes of B1B78 Mitsubishi

  1. Faulty passenger seat weight sensor
  2. Wiring or connector issues in the sensor circuit
  3. Corrosion or damage to the sensor components
  4. Software malfunction in the airbag control module
  5. Impact or physical damage to the sensor from a previous collision

Symptoms of B1B78 Mitsubishi

  1. Airbag warning light illuminated on the dashboard
  2. Airbag system error message displayed on the instrument cluster
  3. Inconsistent airbag deployment during testing
  4. Passenger airbag off indicator illuminated when a passenger is present
  5. Vehicle failing safety inspections due to airbag system malfunction

How to Fix B1B78 Mitsubishi

  1. Begin by diagnosing the specific cause of the issue using a diagnostic scanner to retrieve the fault codes.
  2. Inspect the passenger seat weight sensor and its wiring for any visible damage or corrosion.
  3. Test the sensor's functionality by applying weight to the seat and checking for proper signal transmission.
  4. If the sensor is faulty, replace it with a new OEM part to ensure proper functioning.
  5. Clear the fault codes from the airbag control module and perform a system reset to ensure the issue is resolved.

Cost to Fix B1B78 Mitsubishi

The typical repair costs for addressing the B1B78 Mitsubishi code can vary depending on the specific cause of the issue. On average, replacing the passenger seat weight sensor can cost between $200 to $500, including parts and labor. However, additional costs may apply if there are wiring or connector issues that need to be addressed. It's advisable to consult with a certified technician for an accurate estimate based on the vehicle's make and model. Keep in mind that labor rates at auto repair shops can vary, so it's recommended to research local rates for a more precise cost estimate.

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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 B1B78 Mitsubishi Code

1. What does OBDII code B1B78 for Mitsubishi indicate?

The code B1B78 specifically refers to the Passenger Seat Weight Sensor 3 Left Front Performance issue in a Mitsubishi vehicle.

2. What are the common symptoms of a B1B78 code in a Mitsubishi?

Common symptoms of the B1B78 code may include the airbag warning light illuminating on the dashboard and potential issues with the passenger seat belt reminder system.

3. What can cause the B1B78 code to trigger in a Mitsubishi?

The B1B78 code is typically triggered by a fault in the passenger seat weight sensor, which measures the weight of the occupant to determine if the airbag should be activated.

4. How serious is the B1B78 code in a Mitsubishi?

While the B1B78 code may not directly affect the drivability of the vehicle, it is important to address this issue promptly to ensure the proper functioning of the airbag system in the event of a collision.

5. Can I continue driving my Mitsubishi with a B1B78 code?

It is not recommended to drive the vehicle with an active B1B78 code, as it may indicate a problem with the airbag system, which is crucial for occupant safety in the event of an accident.

6. How can I diagnose and repair a B1B78 code in my Mitsubishi?

Diagnosing and repairing a B1B78 code usually involves checking the passenger seat weight sensor and its wiring for any faults, replacing the sensor if necessary, and resetting the fault code with a diagnostic tool.

7. Can I reset the B1B78 code in my Mitsubishi without fixing the issue?

Resetting the B1B78 code without addressing the underlying problem with the passenger seat weight sensor is not recommended, as the issue may persist and compromise the safety features of the vehicle.

8. Is the repair for a B1B78 code in a Mitsubishi expensive?

The cost of repairing a B1B78 code in a Mitsubishi can vary depending on the extent of the issue and the specific components that need to be replaced. It is advisable to consult a professional mechanic for an accurate estimate.

9. Are there any DIY tips for troubleshooting a B1B78 code in a Mitsubishi?

While basic troubleshooting steps like checking the sensor connections and wiring can be done by DIY enthusiasts, diagnosing and repairing the B1B78 code may require specialized tools and expertise best handled by a professional mechanic.

10. How often does the B1B78 code occur in Mitsubishi vehicles?

The occurrence of the B1B78 code in Mitsubishi vehicles can vary, but it is a relatively common issue associated with the passenger seat weight sensor system, especially in older models or vehicles that have been involved in accidents.

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