Comprehensive Diagnostic Guide for OBD-II Code B0105

Important Notes

• B codes are OBD-II Body/System codes. The precise, manufacturer-specific meaning of B0105 is not provided , so treat B0105 as a body-system fault code that could relate to airbag/SRS circuitry or occupant-sensing components. Always consult the OEM service information for the exact definition and procedure for your vehicle.
• Because B0105 is typically associated with body/SRS components, exercise strict safety precautions when working near airbag systems. Do not probe or disconnect airbag-related components with the system armed. Follow standard safety practices for SRS work (disabling power to the system, waiting the recommended time before handling modules, etc.).
• If available, verify the code against OEM decoding.

1) Code definition and context

• Category: B codes = Body systems. These codes typically involve occupant safety system components (such as airbags, seat sensors, restraints) or other body-related circuits. The exact meaning of B0105 varies by manufacturer, so you should confirm with the vehicle's OEM service information.
• Commonly involved areas for B-series codes in general include airbag deployment loops, squib circuits, seat occupancy or weight sensors, and related harness/connectors. However, the precise B0105 definition should be verified in OEM documentation for the specific vehicle.

2) Symptom descriptions (informed by typical user reports)

• Airbag/SRS warning light is on or blinking on the instrument cluster.
• DTC B0105 is present when scanned, sometimes with related SRS/occupant-sensing codes.
• No obvious driveability problems (the car may operate normally, with the only symptom being the SRS warning).
• In some cases, customers report intermittent illumination of the SRS light or codes related to seating, harnesses, or sensors that come and go with seat adjustment or passenger presence.
  Note: These symptom patterns reflect common user complaints for body/SRS codes in the field, but the exact B0105 symptom set depends on the OEM's implementation.

3) Probable causes and relative likelihood

• Faulty or damaged airbag or SRS wiring/connectors (20-40%)
  • Damaged harnesses or pinched wires under seats or in door sills; corroded connectors; water intrusion.
• Faulty occupant classification/seat weight sensor or related seat electronics (20%)
  • Occupant detection systems can cause B-codes if the sensor circuit or calibration is off.
• Faulty SRS control module or related software (10-20%)
  • Module fault or fault memory in the airbag control unit; requires reset or software update after repair.
• Intermittent or harness-related connection issues (5-15%)
  • Loose grounds, intermittent connector seating, vibration-related opens/closes.
• Shorted squib/deployment loop or damaged airbag components (5-10%)
  • An actual deployment loop fault can trigger B0105; servicing usually requires module and/or squib work.
• Software calibration or configuration issue (5%)
  • In some cases, post-replacement calibration or module re-learning is needed.
    Note: The above are generalized probabilities for body/SRS-type codes in the absence of vehicle-specific data. Always reference OEM fault trees for your exact model.

4) Diagnostic plan (step-by-step)

Safety: This is a safety-critical system. Treat any SRS-related fault seriously. Follow OEM safety procedures for SRS work.

• Preliminary checks
  • Confirm current status: Use a scan tool to verify B0105 is current (not a history/confirm code) and review freeze frame data.
  • Check for related codes: See if there are other B codes or P/C codes that point to a subsystem (e.g., seat sensor, wiring, module, deceleration data, etc.).
  • Visual inspection: Inspect seat wiring harnesses (especially under front seats), connectors, ground points, and door/side impact sensor wiring for damage, corrosion, or pinches.
• Safety-driven steps before probing or disconnected work
  • Disconnect the negative battery cable and wait the OEM-recommended time before working on airbag/SRS components.
  • Discharge static electricity, avoid metal jewelry, and use proper insulated tools.
  • Do not force connectors or pry on airbag harnesses; ensure the system is truly de-energized.
• Electrical and wiring checks
  • Inspect primary airbag harnesses for damage, pinched wiring, and connector security at seat-base connectors, door harnesses, and the SRS control module.
  • Check for damaged insulation, water intrusion, or corrosion at connectors and ground points.
  • Measure continuity and resistance on suspected circuits with a known-good module disengaged if applicable, taking care not to short the deployment circuits.
• Sensor and seating system checks
  • If the vehicle has an occupant classification system (weight sensor or occupancy sensor in the seat), check the sensor wiring and the seat electronics; verify sensor resistance values per OEM specs if available.
  • Confirm seat position and occupant configuration are within OEM calibration ranges; re-seat occupants if necessary (only as directed by OEM procedure).
• SRS module checks
  • Retrieve fault memory from the SRS/airbag control module (ACU/BCM) and check for fault codes or stored fault histories.
  • If a software/firmware issue is suspected, confirm OEM service bulletin or update availability and perform software update or reflash as directed.
• Testing recommendations (non-destructive)
  • Use OEM scan tools or approved testers to retrieve live data for sensor circuits, squib currents, and door/seat sensor data if the OEM provides live parameter data.
  • Do not perform any power-on "live" squib testing outside of OEM-approved procedures.
• Confirming repair necessity
  • Clear codes only after the repair has been completed and the fault is verified as resolved by a short drive and re-check of DTCs (or as OEM procedure requires). Do not rely solely on clearing the code to "fix" the problem.
• OEM-specific steps
  • For B0105, OEM service data will define the exact meaning (e.g., specific sensor or loop). Always consult the vehicle's service information for exact definitions, testing procedures, and replacement procedures.

5) Suggested repair actions (scope, not vehicle-specific)

• If the fault is traced to a damaged harness or connector:
  • Repair or replace damaged wiring, secure harness routing, replace damaged connectors, and ensure proper mating forces.
• If the fault is in the occupant detection/seat weight sensor:
  • Repair or replace the seat sensor components as per OEM instructions; recalibrate or re-learn seating sensor if required.
• If the fault is in the airbag control module or squib circuit:
  • Replace defective airbag modules, squibs, or the control unit per OEM guidance; follow proper airbag replacement procedures including module reprogramming if required.
• If a software/firmware issue is identified:
  • Update or reflash the airbag/SRS module per OEM procedures; clear codes only after confirming the fault is addressed.
• After repair:
  • Reconnect battery, perform the OEM procedure to re-initialize or re-learn the system if required, and re-scan to confirm that B0105 is cleared and no new codes appear.
• If the OEM requires replacement of a safety component:
  • Use OEM-approved parts and follow the specific replacement and seating/airbag calibration instructions.

6) Post-repair verification and testing

• Scanning after repair: Confirm DTCs are cleared and the SRS light remains off during ignition cycle and driving. If the SRS light returns, re-check for wiring, connectors, and any short/open circuits.
• Functional test: On OEM tooling, verify live data for seat sensors, squib current (if applicable) and module health.
• Customer-facing check: Explain to the vehicle owner that SRS issues can be safety-critical and that the system should be tested and validated to OEM standards.

7) Documentation and data collection

• Record the following for the service record:
  • Vehicle identification (VIN), date, mileage
  • Codes read (B0105 and any related codes)
  • Related wiring/harness/seat components inspected
  • Measurements taken (resistance, voltages) and tool used
  • OEM repair steps performed (parts replaced, software updates, calibrations)
  • Confirmation test results (DTC status, PSM/SRS light status)

8) Notable considerations

• The OBD-II framework classifies DTCs into P (Powertrain), B (Body), C (Chassis), and U (Network) categories; B codes cover body/safety or occupant-related systems, reinforcing the expectation that B0105 pertains to SRS/body-related circuitry.
• For precise meaning, rely on OEM service information; general guidance and definitions can be supported by standard code mappings but are not a substitute for OEM data.

9) Quick reference summary

• What it is: B0105 is a body-system DTC; exact OEM meaning varies by vehicle, commonly linked to airbag/SRS or occupant sensing circuits.

• Symptoms: SRS warning light behavior; diagnostic trouble code present; potential seat/wiring concerns.

• Likely causes (order of probability is vehicle/condition dependent): wiring/connectors; occupant sensor/seat weight sensor; SRS module; intermittent connections; deployment loop/component faults; software calibration.

• Diagnostic approach: confirm current code, inspect wiring and connectors (especially under seats), check occupant sensor systems, test modules per OEM, respect safety requirements, verify OEM calibration/re-learn if required.

• Repair approach: fix wiring/connectors, replace faulty sensors or modules as directed, perform OEM software update if needed, re-test and clear codes only after verification.

• Verification: re-scan, confirm no codes and SRS light off in ignition cycles; document results.

• OBD-II and DTCs, including the categorization of codes and the existence of body (B) codes: Diagnostic Trouble Codes; Powertrain Codes.

• Emissions Testing coverage indicates the broader context of how DTCs relate to emissions and vehicle diagnostics, reinforcing standard diagnostic workflows in the OB-II framework.

• GitHub definitions provide standard, community-informed mappings of OBD-II codes (used here to reinforce the concept that B-codes denote body systems and to emphasize cross-source consistency).

Notes for future refinement

Safety Considerations

• Airbag/SRS faults are safety-critical. Only perform repairs and testing with the system de-energized according to OEM procedures, and verify functionality with approved equipment and procedures.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

---