AU
B168000

DTC B168000 indicates the SRS (Supplemental Restraint System) control module detected a communication interruption or physical disconnection between the Passenger Airbag Disable (PAD) switch and the main control unit — Seal U

Safety System

DTC B168000 indicates the SRS (Supplemental Restraint System) control module detected a communication interruption or physical disconnection between the Passenger Airbag Disable (PAD) switch and the main control unit.

The PAD switch typically mounts in the center console or near the glovebox to manually disable the front passenger airbag (e.g., when installing a child safety seat).

The SRS module triggers this fault code if it fails to receive the switch resistance signal (typically a specific resistance range, such as 2kΩ-5kΩ indicating different states) within a predetermined time, or if it detects an open circuit (infinite resistance).

This fault forces the front passenger airbag system into fail-safe mode and continuously illuminates the instrument cluster airbag warning lamp.

During a collision, the front passenger airbag may fail to deploy or exhibit unpredictable behavior, severely compromising passive safety.

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Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Loose, disconnected, or poor contact at the front passenger airbag deactivation switch wiring harness connector, especially if incorrectly reconnected after removing and installing the glove box or center console.
  • 2Continuous chafing of the floor or instrument panel wiring harness against moving parts, such as the front passenger seat slide rails and hinges, causes an open circuit, or the internal copper wire breaks while the insulation remains intact (hidden open circuit).
  • 3Internal contact oxidation, spring failure, or mechanical binding within the airbag deactivation switch causes the resistance value to fall outside the standard range (normally 2.5kΩ-4.8kΩ, depending on switch position).
  • 4Short to ground or short to power in the communication circuit between the SRS control module and the switch causes abnormal signal voltage (normal signal voltage is a 0-5V pulse or within a specific analog voltage range).
  • 5Loose front passenger airbag module connector (located inside the instrument panel) triggering an associated communication fault when sharing a ground or signal line with the switch circuit.
What To Do
  • 1
    Connect the BYD VDS2000 or Launch X-431 diagnostic tool. Enter the SRS system to read DTC B168000 and freeze frame data. Confirm the vehicle conditions when the fault occurred (voltage, temperature, mileage). Attempt to clear the DTC to determine if the fault is intermittent.
  • 2
    Visually inspect the front passenger airbag deactivation switch near the centre console or glovebox. Confirm the switch body has no physical damage. Verify the wiring harness connector is fully seated and the locking mechanism is securely engaged. If necessary, disconnect the connector and inspect the terminals for backing out, oxidation, or deformation.
  • 3
    Measure the switch body resistance with a multimeter: in the 'ON' (airbag enabled) position, the resistance should be approximately 2.0-2.5 kΩ; in the 'OFF' (airbag disabled) position, it should be approximately 4.0-4.8 kΩ (refer to the specific model's workshop manual for standard values). If the resistance is infinite or zero, replace the switch body.
  • 4
    Disconnect the SRS control module connector and the switch connector. Measure the wiring harness continuity between them. Inspect the floor wiring harness for wear at the front passenger seat slide rail and the dashboard frame pinch points. Wiring harness resistance must be less than 1 Ω, and insulation resistance to ground must be greater than 10 MΩ.
  • 5
    Check the SRS control module power supply (constant +B) and ground (GND) for secure connections, and inspect the module connector pins for green copper corrosion. Clean with electronic contact cleaner if necessary.
  • 6
    After repairing or replacing the faulty wiring harness/switch, reconnect all connectors, clear the fault codes, and turn the ignition switch to the ON position. Verify the instrument cluster airbag warning lamp turns off after 6 seconds. Perform a system self-check: toggle the front passenger airbag deactivation switch 3 consecutive times. Confirm the SRS module correctly recognizes the status changes and no fault codes reappear.
  • 7
    Perform final verification: Use the diagnostic tool to read the SRS system data stream, confirm 'Passenger Airbag Status' matches the actual switch position, and perform a simulated crash test (diagnostic tool function only; does not trigger the actual airbag) to confirm normal system response.
Real-World Cases
BYD DTC AI Analysis

Aftermarket centre console modification loosened the switch connector

✓
A 2019 BYD E2 owner reported that the airbag warning light on the instrument cluster had suddenly illuminated. Technicians used a VDS scan tool to retrieve DTC B168000. When asked, the owner said a large centre touchscreen had been installed at a modification shop the previous day. Disassembly and inspection found that during centre console removal, the installers had pulled the 2-pin connector for the passenger airbag disable switch (located to the right of the glovebox) loose, breaking the locking tab. Technicians reconnected the connector and used cable ties to secure the wiring harness routing. The fault was resolved after clearing the DTC. Mark all airbag-related wiring harnesses during future modifications to prevent rough disassembly and installation.
BYD DTC AI Analysis

Qin EV wiring harness open circuit caused by seat rail wear

✓
2019 Qin EV, 30,000 km. DTC B168000 occurring intermittently, with increased frequency on rough roads. Initial inspection found no connector faults. Removed the passenger seat and found that the floor harness had chafed through its insulation at the seat rail mounting point from long-term friction. Of the 3 internal wires, 2 had completely broken (copper strands broken but the insulation intact, causing an intermittent open circuit). Stripped back the harness, re-soldered the broken wires, insulated with double-layer heat-shrink tubing, rerouted the harness to clear the seat rail travel path, and added corrugated tubing for protection. Fault completely eliminated.
BYD DTC AI Analysis

E3 airbag disable switch failed due to internal oxidation

✓
2020 BYD E3, 2 years old, operated in a southern coastal city. DTC B168000 persisted and would not clear. Power supply at the switch harness connector measured 12 V (normal), but the signal line showed no change. Removed the switch assembly (right side of centre console, keyhole or button type) and disassembled it. Internal contacts were severely oxidised from humidity; resistance measured in the megaohm range (normal: kiloohm range). Fitted a new passenger airbag deactivation switch (part number may be K85-XXXXXX, verify against specific vehicle configuration). Performed recalibration and the fault cleared. Advised the owner to avoid placing liquids in the cup holder to prevent fluid ingress into the switch.
BYD DTC AI Analysis

Qin EV poor grounding after accident repair

✓
2019 Qin EV. Following front collision repairs, the SRS system stored DTC B168000 and multiple communication faults. Technicians found that the repair shop had not properly tightened the SRS control module ground wire (typically located on the left side of the dashboard frame) during the accident repair. This caused unstable power supply to the module and triggered a false warning for passenger airbag switch disconnection. They reconditioned the ground wire contact surface by grinding away paint and oxidation, then used a torque wrench to tighten the ground bolt to the specified torque (usually 8–10 N·m). After clearing all fault codes, B168000 did not reappear. This case is a reminder that accident repairs must strictly follow circuit diagrams to restore all ground points.
Other Seal U 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.