Diagnostic Guide: OBD-II Code B0149

Important Notes

• Code prefix: B codes are "Body" domain DTCs in OBD-II terminology. The first character indicates the subsystem (Body). The exact OEM-defined description for a given B0149 is OEM-specific and not provided in the summarized sources you supplied. For the precise fault description, you'll need OEM service information or a manufacturer-specific database. In other words: B0149 is a body-domain DTC, but the exact fault description depends on the vehicle make/model.
• Sources consulted: The core structure and meaning of OBD-II trouble codes (P/B/C/U) come from the OBD-II overview in Wikipedia (Diagnostic Trouble Codes; Powertrain Codes). The general reference supports how to treat and approach DTCs, but it does not supply a vehicle-specific description for B0149. See citations: Wikipedia - OBD-II, Diagnostic Trouble Codes; Wikipedia - OBD-II, Powertrain Codes. For standard code formatting and domain definitions, GitHub definitions are noted as a reference in your instructions (OEM-specific details typically reside there as well).
• Real-world symptoms and likelihoods: Because don't include a catalog of B0149 descriptions or vehicle-specific complaints, the diagnostic guide that follows combines general DTC troubleshooting practice with safe, field-proven steps applicable to body-domain codes. If you have access to OEM service data or a vehicle-specific code library, replace the generic steps with model-specific procedures.

1) Quick code reference and what you're facing

• Code type: B0149 (OBD-II trouble code, Body domain). The exact fault description (what B0149 means for your vehicle) is OEM-specific and not defined . Use the scan tool's code description field plus OEM service data to identify the precise fault (for example, which body sub-system is implicated-airbags/occupant sensing, lighting, interior control modules, door modules, etc.).
• Typical real-world pattern (generalized): When a body-domain code appears, symptoms can involve interior electrical faults, occupant sensing/airbag system interactions, lighting/controls in the vehicle interior, or other body modules. The exact symptom will depend on which body sub-system the OEM associates with the B0149 code for that model.

2) Safety advisory (especially if airbag/SRS is involved)

• If the B0149 code could be related to the airbag/SRS (body domain), treat it as a safety-critical item. Airbag systems can deploy or fail to deploy, affecting occupant safety.
• Do not work on or assume serviceability of SRS components without proper training and procedures. When working near airbag wiring, always follow SRS safety protocols: disconnect power, wait for capacitors to discharge, use proper PPE, and avoid static discharge. If in doubt, consult OEM SRS procedures or a qualified technician.

3) Symptoms you might encounter (informing your symptom descriptions)

• Airbag/SRS warning light illuminated or intermittent.
• Interior body-domain fault indications (e.g., signals from a seat module, occupant detection system, or interior lighting control).
• Intermittent or constant loss of function in related interior electronics (dash controls, door modules, or occupant-sensing components).
• No obvious external symptom, but DTC stored and possibly a fault in the body control network or a specific body-subsystem sensor/actuator.

4) Diagnostic flow (step-by-step approach)

• Step 1: Validate the DTC

  • Retrieve DTCs with the ignition in run position and the engine off, then perform a fresh scan to confirm B0149 reappears.
  • Note any freeze-frame data and any accompanying DTCs that may indicate related subsystems (e.g., other B codes or U codes).
  • Check for any OEM-specific subcodes or extended data that your scanner reports.

• Step 2: Gather vehicle context

  • Identify the vehicle make, model, year, and trim. Check whether the B0149 description is OEM-specific for that model.
  • Review any recent work that touched body modules, wiring harnesses, seating components, airbag related hardware, or interior wiring.

• Step 3: Visual and mechanical inspection

  • Inspect wiring harnesses and connectors in likely body sub-systems indicated by the OEM description (for example:
    • Occupant classification system (seat sensor cushions, sensors, and connectors under seats).
    • Airbag wiring harnesses and crash-sensor connections.
    • Interior lighting and control modules wiring.
    • Door modules, instrument cluster, passenger-side electronics, or other body controllers relevant to interior functions.)
  • Look for signs of moisture intrusion, corrosion, damaged insulation, pin bent/broken terminals, or loose connectors.

• Step 4: Check power and grounds

  • Verify supply voltage, ground reliability, and key-on battery maintenance for body control modules involved with the suspected subsystem.
  • Inspect fuses and mini-relays related to interior electronics and SRS components.

• Step 5: Interrogate live data and component function

  • With a compatible scan tool, monitor live data from suspected body modules and sensors (e.g., seat occupancy sensor readings, seat belt buckle circuits, airbag diagnostic status, door module data, interior lighting control outputs).
  • Check for intermittent data, fault flags, or out-of-range sensor values that correlate with the DTC.

• Step 6: Perform targeted testing

  • If the OEM description points to a specific sensor or actuator, perform manufacturer-recommended tests (e.g., seat occupancy sensor calibration or seat module self-test, door module communications test, etc.).
  • For sensor/actuator concerns, perform continuity and resistance checks on suspected wiring harness segments, connectors, and grounds using a digital multimeter.
  • If an airbag/SRS path is implicated (and you're trained to service it), follow OEM procedures for inspecting the SRS wiring, harness routing, and connectors without discharging or misconnecting the system.

• Step 7: Repair or replace affected components

  • Clean and reseat connectors; repair or replace damaged wiring, connectors, or seals.
  • Replace failed components identified by OEM test procedures (e.g., seat occupancy sensor, door module, interior control module) per service data.
  • If necessary, reprogram or relearn/calibrate modules per OEM requirements (e.g., seat occupancy sensor calibration, door module reinitialization).

• Step 8: Clear codes and verify

  • Clear the DTC and perform a road test to verify the fault does not reoccur.
  • After repair, confirm all related monitors pass during driving and that any SRS-related lights return to normal operation if applicable.

5) Probable causes and likelihoods (experience-based estimates due to lack of OEM-specific data )

Note: These percentages are rough, model- and system-dependent. They reflect typical patterns seen with body-domain DTCs in field experience and are not vehicle-specific diagnoses.

• 40% Loose, damaged, or corroded wiring/connectors in the implicated body subsystem (common for body-domain faults where harness integrity is critical).
• 25% Faulty or intermittent sensor/actuator in the suspected body sub-system (e.g., seat occupancy sensor, door module, interior control module).
• 20% Faulty body control module or related controller (electrical fault within the ECU/BCM/OCS or communication bus).
• 10% Moisture intrusion or water-related damage to interior electronics or connectors.
• 5% Other issues (e.g., failed fuses, relay faults, or incidental problems introduced by prior work).

6) Special notes on documentation and sources

• Code structure and domain: For general understanding of OBD-II codes and the fact that B codes are body-domain issues, see the OBD-II Diagnostic Trouble Codes discussion in Wikipedia. These sources explain the code prefixes and the broad approach to diagnosing DTCs.
  • Wikipedia: OBD-II - Diagnostic Trouble Codes
  • Wikipedia: OBD-II - Powertrain Codes
• OEM-specific meaning: The exact meaning of B0149 is OEM-specific and not provided . To interpret B0149 precisely, consult OEM service information, vehicle-specific diagnostic guides, or GitHub repositories that map engine/vehicle codes to statements used by the manufacturer.
• If you're using a GitHub-based code reference, expect a mapping where B0149's description will be tied to a specific body-subsystem (e.g., occupant sensing, airbags, or interior body control). Use that description to tailor the diagnostic flow above to the exact subsystem.

7) What to tell the customer (summary for a quick brief)

• A body-domain fault code B0149 has been stored. The exact fault is OEM-specific, so we'll need to pull the OEM service data for your exact vehicle to know which body sub-system is implicated.
• Current plan: re-scan to confirm the code, review freeze-frame data, inspect related wiring and connectors, test the suspected body-subsystem sensors/modules, perform any required calibration or reseating, and repair any damaged harnesses or components.
• Safety note: If the code relates to airbag/SRS components, we will follow proper safety procedures and proceed only if appropriately trained and equipped. We may need to involve a credentialed technician if SRS work is indicated.

8) References (for quick lookup)

• OEM service data and GitHub code mappings: not included , but recommended for exact B0149 descriptions. Use these when you have access to manufacturer-specific diagnostic data.

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.

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