AU
B168111

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

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 — Qin Plus
  • 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.
  • 2Long-term friction between the under-seat wiring harness and the slide rail or bracket damages the insulation, exposing copper wire that contacts the vehicle body metal and causes a short to ground.
  • 3Liquid corrosion (spilled drinks, water ingress) or an internal circuit fault damages the sensor, causing 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 missing or incorrect, such as failing to perform the standard calibration procedure (no-load/load calibration) after disconnecting power.
What To Do
  • 1
    Use a dedicated BYD diagnostic tool (VDS2000 or Launch X431) to read the SRS system fault codes, determine if B168111 is a current or history 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. Focus on the wiring harness behind the seat slide rails and at the mounting points for abrasion or damaged insulation. Use a multimeter to measure circuit continuity and resistance to ground (normal value > 10 MΩ). Shake the wiring harness to simulate vibration and check for resistance fluctuations.
  • 4
    Measure the seat occupancy sensor resistance (normally about 2-3kΩ; refer to the vehicle repair manual for exact specifications). Check the sensor surface for signs of liquid corrosion. Verify the sensor supply voltage (usually 5V) and signal output are normal.
  • 5
    Repair the wiring harness based on the inspection results (wrap the damaged area with heat shrink tubing, replace the connector, or solder securely) or replace the sensor assembly (record the old sensor serial number).
  • 6
    After 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), then perform a 75kg load calibration (use standard weights or an adult occupant), and verify the data stream shows the occupancy status changes correctly with the load.
  • 7
    Perform a road test or adjust the seat position multiple times. Confirm the fault lamp 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 Qin Plus 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.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.
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.