B0047 is a Body-system Diagnostic Trouble Code indicating a fault related to occupant detection or a closely associated restraint input circuit. SAE J2012-style DTCs identify system-level problems rather than naming a guaranteed failed component; interpretation for B0047 often differs by make, model, and year. You must confirm the root cause with basic electrical and network tests instead of guessing parts. Focus on checking power and ground, signal integrity and plausibility, and any Controller Area Network (CAN) messages that relate to the occupant classification or restraint system before replacing hardware.
What Does B0047 Mean?
This guide follows SAE J2012 formatting; SAE J2012-DA defines the DTC structure and standardized wording and the digital annex contains published descriptions. The code B0047 is shown here without a hyphen FTB suffix — that means no Failure Type Byte is being displayed. If an FTB were present (for example “-1A”), it would act as a subtype byte to narrow the failure mode such as open, short to battery, short to ground, or plausibility/performance variant.
There is no single universal component-level definition for many Body codes including B0047; interpretation varies by manufacturer. B0047 is distinct as a circuit/validation condition: it flags an electrical or plausibility issue in an occupant-detection or restraint-related input rather than categorically declaring a sensor or module defective. Treat the code as a symptom that requires measurement and confirmation.
Quick Reference
- System: Body — occupant detection / restraint input circuit
- Code format: Shown without an FTB; an FTB would indicate a specific failure subtype
- Typical symptom: Airbag/Restraint warning lamp or occupant-detection errors
- Primary tests: Power, ground, signal voltage, continuity, and CAN message plausibility
- Safety: Treat restraint circuits as live; follow safe service procedures before disconnecting
- When to suspect module: Only after wiring, power, ground, and signal tests confirm good
Real-World Example / Field Notes
In the workshop you’ll often see B0047 appear after a seat swap, upholstery service, or a water spill. These events commonly associated with the code can introduce connector corrosion, pin contact loss, or altered sensor pad resistance. One possible cause is a dirty or compressed connector making intermittent contact that changes the occupant-sensor signal under load.
Technicians generally start with a live-data scan tool and a recording of the occupant-detection values while sitting in and leaving the seat. Mode $06 and live PID checks can show whether the sensor values move plausibly with occupancy. If data is fixed at an out-of-range value or toggles between valid and invalid rapidly, suspect intermittent wiring or a contaminated connector.
Bench-testing a seat sensor pad (one possible cause) usually shows a measurable change in resistance or voltage between unoccupied and occupied states; lack of change points to harness or sensor failure. If power and ground to the sensor circuit are correct but the module reports implausible values, the issue may be in the input stage of the Body Control Module (BCM) or in message translation on the Controller Area Network (CAN), which then requires further module-focused testing after all external inputs test good.
Symptoms of B0047
- Airbag warning Instrument cluster shows airbag or supplemental restraint system warning lamp illuminated.
- Seatbelt indicator Seatbelt reminder or status does not change when seat is occupied.
- Occupant detection Seat weight/occupant classification reads implausible or intermittent in live data.
- Intermittent behavior Fault appears and disappears with movement, temperature change, or connector manipulation.
- Stored freeze frame Scan tool shows stored data indicating abnormal sensor voltage or circuit fault.
- Related restraints Airbag deployment logic may be inhibited or show degraded status in diagnostic data.
Common Causes of B0047
Most Common Causes
Wiring and connector issues in the occupant detection circuit are commonly associated with B0047. Poor power or ground at the sensor connector, corroded terminals, chafed shielded wiring, or a loose connector at the seat sensor assembly are typical. Faulty sensor modules in the seat cushion or seat occupancy mat are one possible cause but should only be suspected after wiring, power, and CAN/communication checks pass.
Less Common Causes
Less commonly, software calibration, a Body Control Module (BCM) input-stage anomaly, or intermittent Controller Area Network (CAN) messaging problems are associated with this code. Environmental contamination (liquids or foreign objects in the seat) or manufacturing-specific occupant classification calibration mismatches can also produce B0047-like symptoms on some vehicles.
Diagnosis: Step-by-Step Guide
Tools: digital multimeter (DMM), oscilloscope, OEM-capable scan tool with live data and Mode $06, wiring diagram, backprobe pins or breakout box, insulated hand tools, battery maintainer, and a lab-grade power supply or fused jumper leads.
- Retrieve freeze-frame and live data with the scan tool; record occupant sensor voltages, status bits, and any related message counts.
- Verify code B0047 is shown without/with an FTB as applicable and note stored conditions (ignition state, temperature, vehicle speed).
- With key on, engine off, measure reference voltage and ground at the occupant sensor connector using the DMM; compare to specification ranges in the wiring diagram. Look for open/low/high conditions.
- Check continuity from sensor power and ground to the controlling module; backprobe and wiggle harness while monitoring voltage to reproduce intermittent faults.
- Use an oscilloscope to inspect the sensor signal waveform for noise, dropouts, or flatlines—confirm signal plausibility under simulated load (sit on seat or press mat).
- Inspect connectors and harness for corrosion, bent pins, or water intrusion; repair or clean only if tests show high resistance or intermittent contact.
- If wiring and connector tests pass, monitor CAN bus messages for the occupant sensor and related module; verify message frequency and payload plausibility with the scan tool and oscilloscope of the CAN lines.
- Where available, perform a known-good sensor substitution or sensor bench test only after external wiring and communications are verified good.
- Clear codes, perform the required occupancy calibration or relearn if specified by OEM procedures, then road-test while watching live data to confirm the fault does not return.
- If fault persists after all external tests, consider possible internal processing or input-stage issue at the controlling module as a last step.
Professional tip: Always confirm power, ground, and reference signals before replacing a sensor. Intermittent or high-resistance connections can mimic failed sensors; a short bench swap or temporary power/ground confirmation often saves unnecessary parts and confirms true component failure.
These repair options and cost estimates assume you follow a test-driven approach under SAE J2012-DA wording: verify power, ground, reference, signal integrity, and network messaging before replacing parts. Costs below are for typical passenger vehicles in the U.S. and are justified only by specific failed tests or confirmed inspection findings. If an FTB (Failure Type Byte) were present on the DTC it would narrow the subtype; this content treats B0047 at the base-code, system level and ties fixes to measured failure modes.
Possible Fixes & Repair Costs
Low cost: $50–$200 — Typically a connector cleaning, terminal repair, or securing a loose chassis ground. Justified when voltage/continuity checks show intermittent contact, corrosion, or a high-resistance connection at a serviceable splice or connector. Typical cost: $200–$650 — Repair wiring harness sections, replace a damaged airbag/occupant restraint sensor connector, or replace a seat-occupant sensor mat when bench or in-vehicle resistance and signal tests confirm a faulty sensor. High cost: $650–$1,800+ — Module replacement or significant dash/seat disassembly for an internal sensor or wiring harness routed through structural areas. Only justify module replacement after all external power, ground, reference, and signal wiring tests pass and bi-directional CAN/communication checks confirm possible internal processing or input-stage issue. Factors affecting cost: labor time for access (seat removal, dash), parts sourcing (OEM vs aftermarket), and whether module programming is required by the maker. Always document pre- and post-repair measurements (voltage, resistance, scan-tool live data or Mode $06) to validate the chosen repair.
Can I Still Drive With B0047?
You can often drive short distances with B0047, but it depends on the vehicle’s safety system behavior after the fault sets. If the occupant restraint system disables or shows an airbag/seatbelt warning lamp, driving increases risk in a crash because the system may not deploy correctly. Prioritize measured checks: verify if the warning lamp is steady or intermittent, check if the vehicle enters a limp or reduced-safety mode, and avoid long trips until you confirm whether the fault affects deployment readiness.
What Happens If You Ignore B0047?
Ignoring B0047 can leave the occupant restraint system with degraded detection or deployment capability. A persistent circuit or signal fault can prevent proper restraint activation in a crash, and it may also mask new faults that develop later, complicating repairs and safety assessments.
Related Codes
- B0019 – Occupant Restraint Airbag Circuit Fault
- B0018 – Body Circuit Fault — Restraint Sensor Signal
- B0017 – Body Circuit Signal Integrity Fault
- B0016 – Occupant Sensing Circuit Fault (SRS)
- B0014 – Occupant Restraint Circuit Fault
- B0011 – Occupant Restraint Circuit Fault
- B0009 – Restraint System Circuit Fault
- B0008 – Supplemental Restraint System Circuit High
- B0007 – Supplemental Restraint System Circuit Fault
- B0006 – Restraint Deployment Commanded Too Long
Key Takeaways
- SAE J2012-DA defines B0047 at a system level; interpretation varies by make/model/year.
- Test-driven diagnosis: confirm power, ground, reference, signal integrity, and network messages before replacing parts.
- Connector cleaning or harness repair is low cost when measurements show high resistance or intermittent continuity.
- Module replacement is a last resort after all external inputs test good and communication checks are consistent with an internal issue.
- Address promptly — occupant restraint faults affect crash protection and vehicle safety indicators.
Vehicles Commonly Affected by B0047
B0047 is frequently reported on a variety of modern passenger cars and SUVs from manufacturers with advanced occupant detection and multi-stage airbag systems. Commonly seen on vehicles from European and Japanese brands and domestic models with seat-occupancy sensors, the code appears more often where the restraint system uses distributed sensors, complex harness routing, or CAN-based communication. Always confirm vehicle-specific meaning with the factory code list and measurements.
FAQ
Can a loose connector cause B0047?
Yes. A loose, corroded, or partially backed-out connector can produce the signal integrity or intermittent voltage that triggers B0047. Use a digital multimeter to check continuity and resistance at the connector, wiggle-test while watching live data on a scan tool, and inspect terminals for corrosion or bent pins. Repair or replace the connector only after tests show unstable readings or high resistance consistent with intermittent contact.
Can a module be bad if wiring tests good?
Possibly, but only after all external wiring, power, ground, reference, and signal tests pass should you consider an internal module issue. Confirm stable supply voltage, solid ground, correct reference signals, and expected message traffic on the network. If those inputs are within specification and diagnostics still indicate a fault, the module may have an internal processing or input-stage issue; document all test results before replacing.
Is it safe to clear the code and drive?
Clearing the code temporarily may turn off a warning lamp, but it does not fix the underlying fault. If the code clears and returns immediately, the issue is active and should be diagnosed. Driving after a temporary clear is a short-term test only; rely on measured confirmation of stable voltages, continuity, and communication before considering the system restored for safe operation.
How do I prove a repair fixed B0047?
Proof requires pre- and post-repair measurements and scan-tool evidence: show baseline voltage, resistance, or live-data anomalies; perform the repair; then demonstrate corrected values and fault-free operation under the same test conditions. Run an extended drive cycle or relevant self-test routines and verify no return of B0047. Save logs or printed Mode $06/live-data snapshots for documentation.
Is professional diagnosis necessary for B0047?
Not always, but professional diagnosis is recommended when the fault involves hard-to-access wiring, seat removal, or module-level checks. If you can perform basic continuity, voltage, and signal checks and confirm a simple connector or splice issue, you may repair it yourself. For ambiguous network messages or internal module suspicions, a shop with OEM-level scan tools and safety protocols is prudent to ensure correct repair and occupant safety.