Airbag SRS DTC Codes
      Back to home
      1. MyAirbags FAQ's
      2. Airbag Module Reset
      3. Airbag SRS DTC Codes

      Subaru DTC Code B178C

      The diagnostic trouble code (DTC) B178C in Subaru vehicles pertains to the Occupant Detection System (ODS), specifically indicating a calibration issue with the passenger seat's weight sensor. This sensor determines the presence and weight of the passenger to control airbag deployment appropriately.

       

      Common Causes of DTC B178C:

      • Replacement of SRS Components: Installing a new Supplemental Restraint System (SRS) module without proper calibration can trigger this code.
      • Battery Disconnection: Disconnecting the battery may necessitate recalibration of the ODS.
      • Seat Repairs or Replacement: Removing or replacing the passenger seat or its components without subsequent recalibration can lead to this issue.

       

      Recommended Steps to Address DTC B178C:

      1. Perform System Calibration (Re-zeroing):

        • Use a Diagnostic Scan Tool: Connect a compatible scan tool to the vehicle's onboard diagnostics port.
        • Access the ODS Menu: Navigate to the Occupant Detection System section.
        • Initiate Re-zeroing: Follow the on-screen instructions to recalibrate the passenger seat weight sensor.
        • Ensure Proper Conditions:
          • Park the vehicle on a level surface.
          • Adjust the passenger seat to its rearmost position with the backrest upright.
          • Ensure the seat is unoccupied and free from objects.
          • Verify that the passenger seatbelt is unbuckled and not under tension.
        • Complete the Calibration: After successful recalibration, clear any existing codes to reset the system.

      2. Inspect for Additional Faults:

        • Check for Other DTCs: Use the scan tool to identify any other related codes, such as B1650, which also pertains to the ODS.
        • Address Additional Issues: Follow appropriate diagnostic procedures for any other detected codes.

      3. Consult Service Bulletins:

        • Reference Manufacturer Guidelines: Review Subaru's service bulletins for specific instructions related to DTC B178C.
        • Example: Subaru Service Bulletin 18-217-22R provides detailed procedures for addressing DTC B1788, which may offer insights applicable to B178C.

      4. Seek Professional Assistance:

        • Contact a Certified Technician: If the issue persists after attempting recalibration, consult a Subaru-certified technician for further diagnosis and repair.

      Addressing DTC B178C promptly ensures the proper functioning of the airbag system, maintaining the safety of vehicle occupants.