AU
B168D00

DTC B168D00 indicates the Airbag Control Unit (ACU) detects invalid configuration data for Ignition Loop 9 — Seal 6 EV

Safety System

DTC B168D00 indicates the Airbag Control Unit (ACU) detects invalid configuration data for Ignition Loop 9.

In the BYD Qin PRO SRS system, Loop 9 typically corresponds to the front passenger knee airbag or rear seat side airbag circuit, depending on the vehicle configuration level. "Invalid configuration" means the "configuration present flag", "rated resistance parameter", or "capacity type" in the ACU EEPROM data does not match the installed hardware.

This condition also occurs if the ACU detects a load on a circuit marked "not installed", or detects an open circuit on a loop marked "installed".

This fault causes the ACU to enter degraded mode.

During a collision, the ACU may fail to deploy the airbag on this circuit, or it may trigger a fail-safe strategy that restricts overall SRS functionality.

The B168D00 fault code on the Seal 6 EV indicates the airbag control unit has detected invalid configuration data for Ignition Loop 9, typically affecting the front passenger knee or rear seat side airbag circuit. This medium severity issue usually occurs after replacing the airbag control unit or airbag assembly without proper reprogramming, or due to data corruption. Visit an authorised dealer to reprogram the unit. Typical repair cost data is available based on 3 recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1Failed to write configuration data after replacing the Airbag Control Unit (ACU), or wrote data incorrectly (e.g., installing a used ACU with a stored configuration that does not match the original vehicle configuration).
  • 2ACU internal data corrupted after a vehicle collision, or configuration parameters not updated after replacing the airbag assembly (e.g., installing a high-spec airbag in a low-spec vehicle without reconfiguring).
  • 3Poor contact, short circuit, or abnormal resistance in the Circuit 9 wiring harness connector causes the ACU to falsely detect a configuration error (actual hardware does not match configuration).
  • 4ACU software version defect or programming error causing configuration data validation failure.
  • 512 V battery depletion or improper operation during power-off maintenance caused loss or corruption of configuration data in the ACU non-volatile memory.
What To Do
  • 1
    Connect the VDS2000 or a dedicated BYD diagnostic tool to the vehicle, read all fault codes, confirm B168D00 is a current fault (Active), and record the freeze frame data.
  • 2
    Confirm vehicle configuration: Check the vehicle VIN and configuration sheet to verify the vehicle is equipped with the specific component for circuit 9 (knee airbag/rear side airbag).
  • 3
    Check the ACU software version. If a newer version is available, update the software to eliminate false alarms caused by software defects.
  • 4
    Enter the SRS system 'Special Functions' menu and execute the 'ECU Configuration' or 'Write Configuration Data' function. Reconfigure the Circuit 9 status (enable/disable) and parameters based on actual vehicle equipment.
  • 5
    If configuration fails or the fault persists after configuration, disconnect the battery negative terminal. Check the circuit 9 wiring harness connector (usually located under the passenger dashboard or seat). Measure the circuit resistance (standard value: 1.8-2.5Ω) and eliminate any short or open circuits in the wiring.
  • 6
    If the wiring harness is normal but configuration still fails, replace the ACU with a new unit (confirm the part number matches the vehicle configuration). Perform online configuration, coding, and enter the security verification code (PIN).
  • 7
    Reconnect the battery, clear the fault code, and perform the SRS system self-check (turn the ignition switch to the ON position and wait approximately 10 seconds for the system self-check to complete).
  • 8
    Use the diagnostic tool to perform the 'Collision Output Test' (Simulation Test) to verify the status of circuit 9. Confirm no fault codes are present, then road test the vehicle on a rough road to confirm the fault does not recur.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM ACU not reconfigured after accident repair

✓
A 2019 BYD Qin PRO DM had its airbag control unit replaced with a used unit from the same model at a non-authorised workshop after a front-end collision. The airbag warning light came on, and a scan revealed DTC B168D00. The used ACU came from a base-model car without a passenger knee airbag, while this vehicle is a high-spec variant with one. We ordered a new ACU with the correct high-spec part number. After fitting it, we ran the ‘ACU Replacement’ procedure on the diagnostic tool and programmed the configuration to enable circuit 9. The fault cleared.
BYD DTC AI Analysis

Configuration data lost after software upgrade

✓
A 2018 Qin PRO petrol variant developed an airbag warning light on the instrument cluster after an SRS system software upgrade at the dealership. The diagnostic tool retrieved DTC B168D00. Investigation revealed unstable battery voltage during the upgrade caused the configuration data write to fail. Repair: Checked circuit 9 harness and airbag connector – both normal. Used the diagnostic tool to enter 'System Configuration' and manually changed circuit 9 status from 'Disabled' to 'Enabled' (as the vehicle is actually fitted with a knee airbag). Wrote the configuration, cleared the DTC, and the system returned to normal.
BYD DTC AI Analysis

Loose wiring connection caused misdiagnosis as configuration error.

✓
A 2019 Qin Pro DM had an intermittent airbag warning light while driving. Retrieved DTC B168D00 (intermittent). Inspection found the passenger knee airbag connector (behind the glovebox) had a loose connection due to an assembly fault, causing the ACU to detect intermittent circuit resistance (open circuit state), conflicting with the stored 'installed' configuration. Repair: re-secured the wiring harness, cleaned and tightened the connector terminals. Measured circuit resistance stable at 2.1Ω. Cleared the fault code and monitored for one week with no recurrence.
Other Seal 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV 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.