AU
B16001B

DTC B16001B indicates the SRS (airbag) system detects a range/performance fault in the driver seat occupancy sensor (OCS - Occupant Classification System) signal circuit — Atto 3

Safety System

DTC B16001B indicates the SRS (airbag) system detects a range/performance fault in the driver seat occupancy sensor (OCS - Occupant Classification System) signal circuit.

Specifically, the ACU (Airbag Control Unit) receives a sensor resistance value outside the calibrated range (typically an open circuit, short circuit, or abnormal resistance), or the signal characteristics fail to match the expected logic.

This film pressure sensor, located inside the driver seat cushion or on the inner side of the seat rail, monitors seat occupancy in real time to determine whether to allow full-power airbag deployment during a collision.

If the system cannot confirm driver presence, it illuminates the airbag warning light and may enter a degraded protection mode (such as disabling airbag deployment or reducing deployment force), posing a severe safety hazard.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Fatigue fracture of the seat occupancy sensor membrane pressure-sensing element or an internal open circuit, causing infinite resistance or intermittent fluctuations. Typically occurs after prolonged heavy seat use, modification, or removal.
  • 2Poor connection, unlocked latch, or oxidized terminals at the under-seat wiring harness connector (usually a white 2-pin plug), causing excessive contact resistance (>5Ω) and signal interruption during seat movement or vehicle jolting.
  • 3Excessive pulling of the wiring harness during installation of third-party aftermarket equipment (such as heated/ventilated seat cushions or racing seats) breaks internal copper strands at the connection between the seat wiring harness and body wiring harness, or the aftermarket equipment generates electromagnetic interference affecting the sensor signal.
  • 4ACU (Airbag Control Unit) software calibration defect or sensor zero-point drift causes incorrect signal threshold recognition for specific sensor batches, especially during cold starts.
  • 5Poor fitment or offset installation between the sensor and seat foam prevents pressure transfer, causing the system to falsely detect a circuit fault.
What To Do
  • 1
    Safety Preparation: Disconnect the 12V battery negative terminal and wait 3 minutes for the SRS system to fully discharge to prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use the BYD VDS diagnostic tool to read the detailed fault code status (current/history) and freeze frame data to confirm whether B16001B is a persistent fault.
  • 3
    Visual inspection: Verify the yellow or white SRS wiring harness connector under the driver's seat is fully locked in place. Inspect the wiring harness at the seat slide rails for signs of wear, crushing, or excessive pulling.
  • 4
    Resistance measurement: Disconnect the seat occupancy sensor connector. Use a multimeter to measure the sensor resistance (normal resistance varies with pressure between 800Ω and 1.2kΩ). Measure continuity between the wiring harness terminals; contact resistance must be less than 1Ω.
  • 5
    Interference check: Check for installed third-party smart seat cushions, seat heaters, or similar equipment. Temporarily disconnect power to all aftermarket equipment and test if the fault disappears.
  • 6
    Component replacement: If sensor body resistance is abnormal (infinite or unstable), replace the driver seat occupancy sensor assembly with an OEM part (e.g., part number SC-6980320C). During installation, fit the sensor flush against the foam and secure it with thermally conductive adhesive.
  • 7
    Wiring harness repair: If the wiring harness has an open circuit, replace the complete seat wiring harness assembly. Leave at least 10 cm of slack in the harness to accommodate forward and backward seat movement. Secure the harness with cable ties to prevent pulling.
  • 8
    Software handling: If hardware is normal but the fault is intermittent, connect to the BYD after-sales server and update the ACU software to the latest version. Execute the 'Seat Occupancy Sensor Zero-Point Calibration' and 'Sensitivity Learning' procedures (simulate both occupied and unoccupied states).
  • 9
    System verification: Connect the battery, clear the fault code, and perform a 20 km road test (including bumpy roads and hard braking) to confirm the airbag warning light remains off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin PLUS DM-i loose connection at under-seat connector

✓
Symptom: After starting, the airbag warning light on the dash stayed on. VDS read DTC B16001B (driver seat occupancy sensor circuit fault). No collision history; clearing the code didn’t help. Diagnosis: Inspected the harness under the driver’s seat. Found the white 2-pin connector for the seat occupancy sensor (mounted on the inner side of the slide rail) wasn’t fully locked. Measured contact resistance between the connector terminals and body harness: 5Ω (normal <1Ω). The loose connection caused intermittent signal interruption. Resolution: Disconnected the negative battery terminal for 3 minutes. Removed the seat bolts, unplugged the sensor connector. Cleaned oxidation off the terminals with electrical contact cleaner. Reconnected the plug, making sure the lock clicked in. Secured the harness to the seat frame with cable ties. Cleared fault codes and test drove 20 km — the fault didn’t come back.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Pro seat occupancy sensor unit damaged

✓
Symptoms: The airbag warning light illuminated intermittently, particularly when driving over rough surfaces or during heavy braking, and might extinguish automatically after the vehicle sat idle. A VDS scan revealed DTC B16001B, with historical records showing this fault had occurred 12 times, all intermittent. Diagnosis: Inspected the wiring harness beneath the driver's seat – the harness appeared in good condition and the connector was secure. Removed the driver's seat, stripped back the upholstery and foam, and extracted the film pressure sensor. Measured the sensor's static resistance with a multimeter; the reading showed open circuit (normal range should vary between 500Ω–2kΩ). When gently flexing the sensor wiring, the resistance reading fluctuated occasionally. Determined the internal film circuit had suffered a fatigue fracture due to prolonged compression. Resolution: Replaced the genuine driver seat occupancy sensor assembly (Part No: SC-6980320C). Applied special thermal conductive adhesive between the sensor and seat foam during installation to ensure proper contact, then reassembled the seat. Performed the 'Seat Occupancy Sensor Zero Calibration' procedure using the VDS and cleared the DTC. A one-month follow-up confirmed the fault had not returned.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Han EV: Seat modification caused wiring harness open circuit

✓
Symptoms: The owner fitted racing bucket seats, and the instrument cluster immediately displayed 'Check Airbag System'. Retrieved fault codes B16001B and B16001C (passenger side). After refitting the original seats, the passenger side fault cleared, but the driver side B16001B remained. Diagnosis: The modification involved forcibly removing the original seat occupancy sensor and overstretching its wiring harness (the transition section from seat to body harness). Stripping back the harness insulation revealed two copper wires completely severed, with only the outer sheath intact. Measured an open circuit between the sensor and the ACU. Resolution: Replaced the complete seat harness assembly (including the occupancy sensor connector) as the break was at the junction of the seat harness and body harness. Re-routed the wiring to specification, leaving at least 10 cm of slack for seat travel. Installed the original seats, cleared fault codes with a scan tool, and ran a system self-test. Fault resolved. Recommendation: If modifying the seats, use an adapter harness that incorporates the occupancy sensor interface.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Third-party seat cushion causing signal interference in BYD Dolphin

✓
Symptoms: After 8 months of use, the airbag warning light came on with intermittent fault code B16001B. The dealership cleared the code, but it returned after 2–3 days of driving with no specific trigger pattern. Diagnosis: Inspected the seat occupancy sensor and wiring harness—both normal. Further inquiry revealed the owner had recently fitted a third-party smart seat cushion with heating and ventilation. Found the cushion's power harness (12V to 5V adapter) routed parallel and tied together with the seat occupancy sensor harness. Disconnected the cushion, road-tested the vehicle for 3 days, and the fault did not recur. Reconnected the cushion and the fault returned within 1 day, confirming electromagnetic interference was distorting the sensor signal. Resolution: Removed the third-party cushion and restored the seat to original condition. Re-routed the under-seat wiring, separating the sensor signal wires from all power lines (including seat heating, ventilation, or aftermarket devices) by at least 15 cm. Wrapped the sensor harness with aluminium foil shielding tape. Cleared the fault code, issue resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Tang DM-i airbag control unit software calibration error

✓
**Symptoms:** Within one week of taking delivery of the new vehicle, the instrument cluster occasionally displayed the airbag warning light, with DTC B16001B stored. The vehicle had no modifications and the seat showed no abnormalities. The fault appeared more often on cold starts and sometimes disappeared after warm-up. **Diagnosis:** Inspected the seat occupancy sensor hardware connections and found them normal; measured resistance values were within specification. Read live data with VDS and found the ACU (Airbag Control Unit) consistently showed the driver seat status as 'Empty', even when occupied, indicating the ACU could not correctly recognize the sensor signal. Consulted BYD Technical Service Bulletin TSB-2023-08 and confirmed that some vehicles from this batch had an ACU software calibration defect causing incorrect recognition of the signal thresholds for a specific sensor batch. **Resolution:** Connected the vehicle to the BYD after-sales server and upgraded the Airbag Control Unit (ACU) software to the latest version (from V2.1.2 to V2.3.5). After the upgrade, performed the 'Seat Occupancy Sensor Sensitivity Learning' procedure (simulating both occupied and unoccupied states). Cleared stored fault codes and tested 10 cold starts; the fault was completely eliminated.
Original source ↗
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For the BYD Song MAX (2017–2019), DTC B1108 indicates a short circuit in the PM2.5 air quality detection module (dust sensor) or its wiring harness. The sensor uses laser scattering to detect in-cabin and outside PM2.5 concentrations and transmits data to the HVAC ECU via the LIN bus or an analog signal. Short circuit conditions include: 1) Sensor power supply wire (+5V/+12V) shorted to ground 2) Signal wire shorted to power or ground 3) Short circuit in the sensor's internal photoelectric detection circuit This fault prevents the automatic climate control from switching between fresh air and recirculation based on air quality. The system enters fail-safe mode (typically forced recirculation). Severe short-circuit current can destroy the HVAC ECU sampling circuit. The system classifies this as a Level 3 severe fault and restricts vehicle operation to prevent electrical fires or controller damage. For other BYD models (such as the Qin EV, E5, and Song DM), B1108 indicates a driver-side sunload sensor fault, reflecting differences in DTC definitions across models.B110811This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.
Data confidence: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself. Sources: [1]