AU
B16A0

DTC B16A0 indicates a fault in the passenger-side Occupant Classification System (OCS) rather than a purely SRS_ECU hardware fault — Atto 8

Safety System

DTC B16A0 indicates a fault in the passenger-side Occupant Classification System (OCS) rather than a purely SRS_ECU hardware fault.

The system uses a pressure sensor matrix integrated into the front passenger seat cushion and the OCS control module to monitor front passenger seat occupancy and weight category (adult/child/empty) in real time, and sends commands to the SRS_ECU to suppress or allow airbag deployment.

The OCS sets DTC B16A0 when it detects an open circuit, short circuit, abnormal signal, or loss of calibration data in the sensor circuit.

This fault prevents the SRS_ECU from accurately determining the front passenger status, posing the following risks: 1) Unnecessary airbag deployment when the front passenger seat is empty, increasing repair costs; 2) Airbag suppression during a collision due to incorrectly identifying the passenger as a child, resulting in inadequate occupant protection; 3) Abnormal seat belt pretensioner operating logic.

The system uses a 5V reference voltage circuit and is extremely sensitive to changes in circuit resistance and connector contact resistance.

The B16A0 fault code on the Atto 8 indicates a fault in the passenger-side Occupant Classification System (OCS), which monitors seat occupancy to control airbag deployment. Severity is medium. Common causes include loose or corroded wiring connectors and physical damage to the seat cushion pressure sensor. Visit an authorised dealer for repair. Typical repair cost data is available based on 5 recorded cases.
5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Seat occupancy sensor (OCS) wiring harness connector loose, oxidized, or corroded by water ingress, causing increased contact resistance or intermittent signal interruption.
  • 2Physical damage to the pressure sensor mat (pressure sensing film) inside the seat cushion, such as punctures from sharp objects, plastic deformation from prolonged heavy loads, or creases.
  • 3Seat adjustment slide rail interferes with the OCS wiring harness during movement, causing harness insulation wear, broken copper cores, or a short circuit.
  • 4Internal fault in the OCS control module ADC conversion circuit, or loss of EEPROM calibration data (common after replacing the seat or airbag control unit without performing the calibration procedure).
  • 5Previous removal or modification of the front passenger seat (e.g., installing seat covers or heating pads) altered sensor load characteristics or stretched the wiring harness.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Fault Confirmation: Use the BYD dedicated diagnostic tool (VDS2000) to read the DTC. Confirm B16A0 is the current fault code. Record freeze frame data (including vehicle speed at the time of the fault, seat status signal voltage, etc.).
  • 3
    Visual inspection: Remove the front passenger seat (if necessary). Carefully inspect the yellow OCS connector under the seat for full engagement, the terminals for green oxidation, and the corrugated wiring conduit for wear or damage at the seat slide rail.
  • 4
    Circuit measurement: Turn the ignition switch to ON (do not start the engine). Measure the OCS sensor supply voltage (standard value: 4.9-5.1V) and signal voltage (approx. 2.0-2.5V when unoccupied; 0.5-4.5V when occupied, varying by weight). Check the circuit insulation to ground and power supply.
  • 5
    Component inspection: Remove the seat cushion cover. Visually inspect the pressure sensor mat for cracks, creases, or signs of liquid ingress. Press the sensor area with your finger and observe if the 'Passenger Seat Weight' value in the diagnostic tool data stream changes linearly with pressure.
  • 6
    Repair action: Depending on the specific fault found, clean oxidized pins using electrical contact cleaner and conductive grease, repair damaged wiring harnesses by soldering and insulating with heat-shrink tubing, or replace damaged sensor pads or the OCS control module.
  • 7
    System calibration: After completing hardware repairs, perform the OCS calibration procedure. Use the diagnostic tool to enter 'SRS System → Special Functions → OCS Calibration'. Follow the prompts to sequentially place no load, a 36kg standard weight, and a 75kg standard weight to perform the three-point calibration. This ensures the system accurately identifies the three states: 'empty seat', 'child', and 'adult'.
  • 8
    Verification test: Clear the fault code and perform a road test (including bumpy roads). Confirm the fault lamp turns off and the seat status in the data stream changes correctly with actual occupancy. Simulate a collision test (use the diagnostic tool to perform a collision output test) and confirm the front passenger airbag control logic operates normally.
Real-World Cases
BYD DTC AI Analysis

Damaged seat occupancy sensor pad on BYD Qin Pro causing B16A0

✓
Symptoms: The airbag warning light on the instrument panel stayed on. The diagnostic tool retrieved fault code B16A0 and could not clear it. Diagnosis: Checked the OCS connector beneath the front passenger seat and found the plug loose. Measured sensor resistance; it fell outside the standard range of 95–105Ω. Removed and inspected the seat, and found the pressure sensor pad partially damaged from prolonged compression by the onboard charger. Solution: Replaced the front passenger seat occupancy sensor assembly (including the pressure sensing pad and OCS control module). Used the diagnostic tool to perform the OCS system calibration procedure: sequentially placed 0kg, 36kg, and 75kg standard weights for the system to learn. Cleared the fault codes and road tested the vehicle. The airbag warning light turned off, and the data stream showed accurate seat status recognition.
Original source ↗
BYD DTC AI Analysis

BYD Song MAX: Loose wiring harness after seat cleaning triggered B16A0

✓
Symptom: The airbag warning light came on suddenly while driving. The owner recalled recently removing the passenger seat for deep cleaning. Diagnosis: Retrieved DTC B16A0-00 (passenger side seat occupancy sensor circuit fault). Inspected the wiring harness beneath the seat and found the OCS module connector not fully seated (tugging during cleaning had left the latch unsecured). Checked live data: passenger seat status showed ‘Unoccupied’ even with an occupant in the seat. Solution: Re-seated the OCS module connector, making sure the latch locked fully with an audible click. Ran the ‘seat occupancy sensor calibration’ using a scan tool. After calibration, the system returned to normal. Cleared the fault code; the fault has not returned.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM: seat rails chafing the wiring harness causing intermittent B16A0

✓
Symptoms: Dashboard displays 'Please Check Airbag System' warning. Intermittent fault, occurring more frequently on rough roads. DTC: B16A0. Diagnosis: Scanned with VDS2000 and confirmed B16A0 current. Inspected passenger seat occupancy sensor wiring and found harness chafing at seat rails; damaged insulation exposed copper conductors, causing intermittent short. Verified OCS control module mounting secure with no pin corrosion. Simulated rough road conditions by shaking harness; DTC status toggled between current and history, confirming fault location. Repair: Repaired damaged wiring (soldered the break and applied double-layer heat shrink insulation). Added abrasion-resistant corrugated tubing for harness protection. Rerouted and secured harness above seat frame to prevent rail contact. Cleared DTC, performed OCS system calibration, and conducted multiple road tests to confirm fault eliminated.
Original source ↗
BYD DTC AI Analysis

BYD Han EV: Creased pressure sensor membrane on new vehicle caused B16A0

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Symptoms: Airbag warning light illuminated on the dashboard after three months of ownership. The scan tool showed DTC B16A0, with the passenger seat registering a fault whether occupied or empty. Diagnosis: Read the fault code as B16A0 - Occupant Classification System Fault. Inspected the OCS module beneath the seat; no external damage and the connector was secure. Checked the live data and found the sensor voltage signal was abnormal, stuck at 4.8V (saturated). Removed the seat and found obvious creasing on the pressure sensor film. The owner had placed a hard suitcase on the seat, which crushed the sensor during loading or unloading. Resolution: Replaced the passenger seat cushion assembly (incorporating the built-in occupant sensor; the sensor and cushion are integrated and cannot be replaced separately). After replacement, ran the OCS initialisation learning procedure using the scan tool. Following the workshop manual, placed 20kg weights (simulating empty seat/child threshold) then 60kg weights (simulating adult threshold) on the seat to perform the calibration test. Confirmed the system correctly distinguishes between the three states.
Original source ↗
BYD DTC AI Analysis

OCS connector pin oxidation fault on BYD e5 taxi

✓
Symptoms: On a BYD e5 taxi at 80,000 km, the airbag warning light illuminated. A diagnostic scan detected DTC B16A0. Diagnosis: Read DTC B16A0. Historical fault records showed five previous intermittent occurrences. Inspected the seat occupancy sensor connector and found obvious green oxidation on the pins (water ingress under the seat from frequent cleaning). Measured the sensor supply voltage: specification is 5 V reference, actual reading was 4.2 V with 0.3 V fluctuation, indicating excessive contact resistance in the harness. Further inspection found a loose intermediate connector between the OCS control module and the sensor. Resolution: Cleaned the oxidised connector pins with electronic contact cleaner. After drying, applied conductive grease to prevent re-oxidation. Re-tightened all connectors, ensuring contact resistance below 0.5 Ω. Cleared fault codes and completed a 20 km road test; the fault did not reappear. Advised the owner to avoid directing water under the seat when cleaning and to use a damp cloth instead of a pressure washer.
Original source ↗
Other Atto 8 Fault Codes
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.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 overview →
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.