AU
B168111

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

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.

The B168111 fault code on the Seal U indicates a short to ground or abnormal signal in the front passenger Occupant Classification System (OCS). This high-severity safety fault affects airbag deployment and may force the passenger airbag off. Common causes include damaged wiring harness connectors or chafed wires shorting to the seat frame. Visit an authorised dealer for repair. Typical repair cost data is available from 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Front passenger seat occupant detection sensor (ODS) wiring harness connector loose, terminal backed out, or locking clip damaged, causing poor contact or intermittent short to ground.
  • 2Long-term chafing between the under-seat wiring harness and the seat rail or bracket damages the insulation. Exposed copper wire contacts the vehicle body metal, causing a short to ground.
  • 3Sensor body damage due to liquid corrosion (spilled drinks, water ingress) or an internal circuit fault causes abnormal signal output.
  • 4Connector seal failure allows rainwater or car wash water ingress, causing pin oxidation and corrosion that creates abnormal resistance.
  • 5Sensor calibration data missing or incorrect, such as failing to perform the standard calibration procedure (no-load/load calibration) after power disconnection.
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 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. Check the harness behind the seat slide rails and at the fixing points for wear 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 if the resistance reading fluctuates.
  • 4
    Measure the seat occupancy sensor resistance (normally about 2-3kΩ; refer to the model-specific workshop manual). 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 according to the inspection results (wrap damaged sections with heat-shrink tubing, replace the connector, and 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), then 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 repeatedly adjust the seat position. Verify the fault light does not illuminate 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 Seal U Fault Codes
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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.