AU
B168111

DTC B168111 indicates the front passenger Occupant Classification System (OCS) detects a short to ground or abnormal signal — Atto 3

Safety System

DTC B168111 indicates the front passenger Occupant Classification System (OCS) detects a short to ground or abnormal signal.

The system uses pressure or capacitive sensors integrated into the seat to monitor passenger occupancy status and weight data to control the passenger airbag deployment strategy.

When the system detects a sensor circuit short to ground, internal sensor damage, or an abnormal signal, it logs this DTC and illuminates the airbag warning light.

Under these conditions, the passenger airbag may enter fail-safe mode (forced off or deployed based on the worst-case scenario) and fail to provide effective protection during a collision.

This is a severe safety fault.

4
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Front passenger seat occupant detection sensor (ODS) wiring harness connector loose, terminal backed out, or locking tab damaged, causing poor contact or intermittent short to ground.
  • 2Prolonged chafing between the under-seat wiring harness and the seat rail or bracket damages the insulation. The exposed copper wire contacts the vehicle body metal, causing a short to ground.
  • 3Sensor damage from liquid corrosion (spilled drinks, water ingress) or an internal circuit fault causes abnormal signal output.
  • 4Plug seal failure allows rainwater or car wash water ingress, causing pin oxidation and corrosion that results in abnormal resistance.
  • 5Sensor calibration data lost or incorrect, such as failing to perform the standard calibration procedure (no-load/load calibration) after disconnecting power.
What To Do
  • 1
    Use the BYD dedicated diagnostic tool (VDS2000 or Launch X431) to read the SRS system fault codes, confirm whether B168111 is a current or historical fault, and check the front passenger occupancy status in the data stream.
  • 2
    Visually inspect the ODS wiring harness connector under the front passenger seat (usually a white 4-pin connector) for looseness, water ingress, or corrosion. Verify the connector locking mechanism is intact and inspect the connector pins for copper corrosion or oxidation.
  • 3
    Remove the seat and inspect the wiring harness routing. Check the harness behind the seat slide rail and at the mounting points for abrasion or damaged insulation. Use a multimeter to measure circuit continuity and resistance to ground (normal: > 10 MΩ). Shake the wiring harness to simulate vibration and check for resistance fluctuations.
  • 4
    Measure the seat occupancy sensor resistance (normally 2-3 kΩ; refer to the vehicle repair manual for exact specifications). Inspect the sensor surface for liquid corrosion. Verify the sensor supply voltage (typically 5 V) and signal output are normal.
  • 5
    Repair the wiring harness based on the inspection results (wrap damaged areas with heat-shrink tubing, replace the connector, or solder to secure), or replace the sensor assembly (record the old sensor serial number).
  • 6
    After completing the repair, clear the fault code and use the diagnostic tool to execute the "Seat Occupancy Sensor Calibration" or "OCS System Configuration" procedure. First, perform a no-load calibration (seat unoccupied, wait 10 seconds). Next, perform a 75kg load calibration (use standard weights or an adult occupant). Verify the data stream shows the occupancy status changes normally with the load.
  • 7
    Perform a road test or adjust the seat position multiple times. Confirm the fault light remains off and the system generates no fault codes.
Real-World Cases
BYD DTC AI Analysis

BYD Qin Pro DM Wiring Harness Poor Contact Case

✓
Symptoms: Airbag warning light stays on constantly after starting the vehicle. DTC B168111 stored. Dashboard indicates passenger seat occupied regardless of actual occupancy, with erratic seatbelt warning logic. Diagnosis: VDS2000 identified an intermittent fault. Removing the passenger seat revealed a loose ODS wiring harness connector (white 4-pin) with a broken locking tab, causing poor contact from driving vibrations. Sensor resistance measured normally at 2.3kΩ but fluctuated when moving the harness. Fix: Replaced the harness connector and soldered the connections. Rerouted and secured the wiring with insulation tape and cable ties to prevent interference with the seat rails. Cleared the DTCs and performed seat occupancy sensor calibration (no load and 75kg load). Road tested for one week with no recurrence.
Original source ↗
BYD DTC AI Analysis

BYD Song PLUS DM-i sensor body damage case

✓
Symptoms: The airbag warning light came on suddenly while driving. DTC B168111 was stored as both a historical and current fault. The passenger airbag indicator showed OFF, and the occupant detection function was inoperative. Diagnosis: Using a Launch X431, live data showed the front passenger occupant status constantly at “0” (unoccupied), with no change when someone sat in the seat. Removing the seat revealed the sensor beneath the foam had liquid corrosion on its surface (the owner had spilled a drink and didn’t clean it promptly). Measured the sensor power supply: 5V (normal). The signal line had no voltage output, confirming the sensor unit was faulty. Solution: Replaced the OEM front passenger seat occupant sensor assembly (K85-6306600). Used VDS to write the sensor serial number and performed ODS calibration (unloaded for 10 seconds → 75kg load for 10 seconds). After clearing the DTCs, live data returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Han EV seat wiring harness wear case

✓
Symptoms: Six months after purchase, the airbag warning light illuminated intermittently, particularly after adjusting the passenger seat fore and aft. DTC B168111 was stored. Occasionally the light went out by itself after the vehicle sat overnight. Diagnosis: Intermittent wiring fault. Removed the seat and inspected the harness at the seat rails. The seat occupancy sensor wiring had chafed through at the fixing point behind the rails, exposing the copper conductors. When the seat moved, the exposed wires contacted the chassis, creating a short to earth. Resolution: Repaired the damaged wiring and covered it with heat-shrink tubing. Rerouted the harness and added corrugated tubing for protection. Secured the harness with dedicated clips to maintain a 20 mm clearance from moving parts. Measured circuit resistance to earth at greater than 10 MΩ. Cleared the DTC and carried out multiple seat adjustment tests — all normal.
Original source ↗
BYD DTC AI Analysis

BYD Dolphin connector water ingress corrosion case

✓
Symptoms: During rainy weather or after car washing, the dashboard intermittently displayed 'Check Airbag System', logging DTC B168111. The warning cleared in dry weather, and the passenger occupancy detection function worked intermittently. Diagnosis: Inspected beneath the seat and found water-damaged carpet (blocked sunroof drain tube). Removed the ODS connector and found green copper corrosion inside. Pin oxidation caused high contact resistance (normal <1 Ω, measured 15 Ω) due to inadequate sealing and prolonged water immersion. Resolution: Cleaned the pins with electronic cleaner and applied conductive grease. Replaced the seal with a waterproof sealing ring. Cleared the blocked sunroof drain tube. Removed standing water and dried the area. Wrapped the connector with waterproof tape. Cleared DTCs and tested sensor recognition accuracy with 25 kg and 75 kg weights – normal.
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.