AU
B168600

DTC B168600 indicates the SRS (Supplemental Restraint System/airbag) control module detects an abnormal configuration status in "Circuit 2" (typically the front passenger-side airbag deployment circuit) — Seal U

Safety System

DTC B168600 indicates the SRS (Supplemental Restraint System/airbag) control module detects an abnormal configuration status in "Circuit 2" (typically the front passenger-side airbag deployment circuit).

In the BYD Qin PRO airbag architecture, the control module determines system status by monitoring circuit resistance (standard value 2.0–3.0 Ω) and configuration data. "Invalid configuration" means the control module reads a circuit resistance outside the threshold (open circuit >10 Ω or short circuit <1 Ω), or detects circuit configuration data that does not match the vehicle VIN or lacks correct coding.

This fault may prevent the passenger-side airbag from deploying properly during a collision.

The system also illuminates the instrument cluster airbag warning light and may disable the entire airbag system to enter fail-safe mode.

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Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Front passenger airbag module internal igniter resistance drift or damage causes abnormal circuit resistance.
  • 2Yellow connector between the floor wiring harness and the airbag module (usually located behind the glovebox or on the right side of the center console) is loose, or has backed-out pins, oxidation, or corrosion due to water ingress.
  • 3Internal open or short circuit in the spiral cable (clock spring) affecting the signal transmission path of circuit 2.
  • 4Outdated SRS control unit (ACU) software version or hardware fault causing false detection during circuit 2 monitoring.
  • 5Corrosion of the airbag wiring harness connector terminals caused by vehicle wading, interior water ingress, or high-humidity environments.
What To Do
  • 1
    Use the BYD dedicated diagnostic tool (VDS2000/VDS3000) to read the complete DTC. Verify B168600 is a current fault, not a history fault, and record the circuit resistance value from the freeze frame data.
  • 2
    Disconnect the battery negative cable and wait at least 3 minutes to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 3
    Remove the glove box or the right side trim panel of the center console. Check the passenger side airbag wiring harness connector (yellow identifier) for looseness, water ingress, or oxidized pins. Clean and reconnect if necessary.
  • 4
    Disconnect the airbag module connector and use a multimeter to measure the resistance of circuit 2 on the wiring harness side. The normal value is 2.0-3.0 Ω. Measure the insulation resistance to ground and to the power supply; it must be greater than 1 MΩ.
  • 5
    Check clock spring (spiral cable) continuity, specifically the circuit 2 pins connected to the passenger-side airbag, and inspect for internal open or short circuits.
  • 6
    If wiring harness measurements are normal, check the SRS control module software version. Compare against the BYD Technical Service Bulletin (TSB) and update to the latest software version if necessary.
  • 7
    After replacing the faulty component (airbag module, wiring harness, or ACU), use the diagnostic tool to perform the 'SRS System Configuration' or 'Airbag Coding' function to ensure the new component matches the vehicle.
  • 8
    Clear the fault code, reconnect the battery, and turn on the ignition. Check that the airbag warning lamp turns off after the self-check, then perform a system self-check cycle to verify.
Real-World Cases
BYD DTC AI Analysis

BYD Qin Pro DM passenger-side airbag connector pin backed out

✓
A 2019 BYD Qin Pro DM with 30,000 km displayed 'Check Airbag System' on the dash. The scan tool read active DTC B168600. Disassembling the passenger side airbag harness revealed the female terminal inside the yellow connector had backed out, driving contact resistance to 15 Ω. After reseating the terminal and applying conductive paste, circuit resistance returned to 2.3 Ω, clearing the fault.
BYD DTC AI Analysis

Qin PRO petrol SRS control module software fault

✓
2018 BYD Qin Pro petrol, no accident history, intermittent B168600 DTC. Inspection found SRS control module had an early software version with a known defect that falsely reports Circuit 2 faults. Updated ACU software to latest version (downloaded from BYD after-sales system), performed configuration write. Fault has not returned.
BYD DTC AI Analysis

Airbag wiring harness corrosion on water-wading vehicle

✓
A Qin Pro DM had previously waded through water up to carpet height. After repair work, DTC B168600 appeared. Inspection found the floor harness waterproof plug under the front passenger seat damaged, allowing moisture ingress that oxidised and blackened the airbag circuit 2 connector terminals. Replaced the floor wiring harness assembly and repaired the waterproofing to resolve the fault.
BYD DTC AI Analysis

Replaced passenger airbag without configuration, causing fault.

✓
After the front passenger airbag was replaced on a Qin Pro, the technician cleared the fault codes without using a diagnostic tool to configure the SRS system. DTC B168600 returned after two days of driving. The technician then performed the 'SRS module configuration' function using VDS2000 and entered the correct vehicle configuration code. The system recognised the new airbag module, completely resolving the fault.
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.