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B16C0

On BYD vehicles, DTC B16C0 indicates a front passenger Occupant Classification System (OCS) sensor fault, not an internal SRS ECU fault — Seal 6 EV

Safety System

On BYD vehicles, DTC B16C0 indicates a front passenger Occupant Classification System (OCS) sensor fault, not an internal SRS ECU fault.

The system detects seat load status using a capacitive or piezoresistive pressure-sensing membrane inside the front passenger seat cushion.

It distinguishes between an adult, a child, or an unoccupied seat to control the front passenger airbag deployment strategy (deployment decision, timing, and force).

When the SRS ECU detects an OCS sensor signal open circuit, short circuit, out-of-range value, or incomplete calibration, it sets this DTC and illuminates the airbag warning lamp.

This fault creates an extreme safety risk: the system may incorrectly identify the seat as unoccupied and disable airbag deployment, or erroneously deploy the airbag when a child seat is installed.

This safety hazard requires immediate repair.

The B16C0 fault code on the Seal 6 EV indicates a front passenger Occupant Classification System sensor fault. Severity is medium, but it affects airbag operation and should be checked promptly. Common causes include a loose or oxidised yellow 2-pin connector under the seat, or damaged wiring from chafing against the seat frame. Visit an authorised dealer for diagnosis, calibration, and repair. Typical repair cost data is available from recorded cases.
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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1Oxidation, loose connection, or poor contact at the yellow 2-pin wiring harness connector under the seat, causing interrupted signal transmission or abnormal resistance.
  • 2Prolonged chafing between the wiring harness and the seat metal frame damages the insulation, causing a short to ground or short to power.
  • 3OCS sensor mat cut, folded, or physically damaged during front passenger seat modification (leather retrim, foam replacement).
  • 4Failure to perform the OCS (Occupant Classification Calibration) procedure after replacing the seat assembly or airbag ECU prevented sensor ID writing or weight threshold calibration.
  • 5Internal sensor circuit aging, corrosion from water ingress, or capacitance/resistance drift causes the output signal to exceed the ECU threshold range (normal no-load value: 2.5kΩ-3.0kΩ).
What To Do
  • 1
    Connect the VDS2000 or X431 diagnostic tool. Access the SRS system to read the fault codes and freeze frame data. Check the 'Passenger Seat Status' and 'OCS Sensor Resistance' values in the data stream to determine if the fault is continuous or intermittent.
  • 2
    Disconnect the yellow connector under the front passenger seat (usually located in front of the seat track). Inspect the pins for oxidation or push-out. Clean the pins with electrical contact cleaner and apply conductive grease. Measure the resistance between the connector terminals (normal no-load resistance is 2.5 kΩ–3.0 kΩ; resistance changes when occupied).
  • 3
    Inspect along the seat wiring harness to the floor harness connection point. Check the contact areas between the harness, seat frame, and slide rails. If wear or damaged insulation is present, cut out the damaged section. Solder an extension wire and apply heat-shrink tubing and waterproof tape for double-layer insulation. Re-secure the harness with cable ties, maintaining a minimum clearance of 20 mm.
  • 4
    If wiring harness continuity is normal but sensor resistance is abnormal (infinite, shorted, or a fixed value that does not change with pressure), replace the front passenger seat cushion assembly (including the integrated OCS sensor mat). Do not disassemble the sensor mat separately for repair.
  • 5
    After replacing components or repairing the wiring harness, access the diagnostic tool 'Special Functions' → 'Passenger Classification System Calibration'. Follow the prompts to sequentially place 5kg (simulating a child seat) and 75kg (simulating an adult) standard weights to complete the sensor zero-point and full-scale calibration.
  • 6
    Clear the fault code and perform a 20-minute dynamic road test (including bumpy roads). Confirm the instrument cluster airbag warning light turns off, the seat status in the data stream correctly switches between 'Empty' and 'Occupied' based on occupancy, and the fault code does not return.
Real-World Cases
BYD DTC AI Analysis

Oxidised wiring harness connector on Tang DM caused intermittent fault

✓
2019 BYD Tang DM, 32,000 km. The airbag warning light on the dash would illuminate intermittently with no set pattern, easily triggered after driving over speed bumps. VDS pulled fault code B16C0 (passenger seat occupancy sensor signal abnormal/open circuit), alternating between current and history. Under-seat inspection found green oxide inside the yellow connector. Resistance measurement showed the sensor open circuit (infinite resistance) when shaken. Cleaned the connector pins, applied conductive grease, and replaced the wiring harness connector (part no. BYD-282104-XXXX). Cleared the fault codes and road tested—issue resolved.
Original source ↗
BYD DTC AI Analysis

Han EV OCS uncalibrated after accident repair

✓
2021 BYD Han EV. After repairs following a right-front side collision, the airbag warning light stayed on constantly. VDS read code B16C0 (front passenger OCS sensor not calibrated); live data showed seat status always 'Empty'. Diagnosis found the accident repair had used a lower-spec salvaged seat, the sensor ID didn't match the vehicle, and the calibration option in VDS was greyed out. Replaced the front passenger seat cushion assembly with a new genuine unit (Part No.: SCEA-XXXXXXXX). Performed passenger classification system calibration using 5kg and 75kg standard weights. Fault cleared after successful calibration.
Original source ↗
BYD DTC AI Analysis

Aftermarket seat modification on Qin Pro caused sensor damage

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2020 BYD Qin Pro. Airbag warning light stayed on after leather seat modification, with DTCs B16C0 (Sensor Performance Range) and B16C1 (Hardware Failure). Disassembly revealed the modification blade had sliced through the OCS sensor mat inside the seat cushion. Resistance measured only 120 Ω (near short circuit). Replaced the genuine front passenger seat occupancy sensor together with the cushion foam (part number: F3-XXXXXXXX). Advised the owner to always transplant the original sensor mat intact during future seat modifications, and then perform the calibration procedure.
Original source ↗
BYD DTC AI Analysis

Song Plus DM-i wiring harness chafing against frame

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2022 BYD Song Plus DM-i, 18,000 km. After starting, the airbag warning light flashes for 6 seconds then stays on continuously, displaying 'Please check airbag system'. DTC B16C0 (passenger seat occupancy sensor circuit short to ground). Inspection found an unsecured wiring harness under the seat, rubbing against the metal frame and causing the 5V supply wire to wear through and short to ground, putting the ECU into protection mode. Repaired the damaged harness by soldering and insulating with heat-shrink tubing, re-secured the harness routing with clearance from the frame, cleared the fault codes, and the data stream returned to normal.
Original source ↗
Other Seal 6 EV Fault Codes
B1108For 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.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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV 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.