AU
B168900

DTC B168900 indicates the SRS (Supplemental Restraint System) control module detects invalid configuration data for deployment loop 5 (typically the right front seat side airbag or right curtain airbag, depending on vehicle trim level) — Atto 3

Safety System

DTC B168900 indicates the SRS (Supplemental Restraint System) control module detects invalid configuration data for deployment loop 5 (typically the right front seat side airbag or right curtain airbag, depending on vehicle trim level).

This constitutes a Configuration Error rather than a simple open or short circuit.

The electrical characteristics of this loop (e.g., igniter resistance, loop integrity detection parameters) do not match the calibration data stored in the ECU.

Possible causes include: loop resistance outside the threshold (>5Ω or <1Ω), incorrect ECU coding, failure to write configuration data after replacing the airbag module, crash data corruption, or a software version mismatch.

This fault may prevent the specific airbag from deploying during a collision and illuminates the airbag warning light.

3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Circuit 5 wiring harness connector loose, oxidized, or terminal pins backed out (on Qin PRO models, Circuit 5 typically routes under the right front seat or at the B-pillar; frequent seat adjustment causes wiring harness fatigue)
  • 2Internal igniter resistance drift or failure in the airbag module (side airbag or curtain airbag for circuit 5) causes the ECU to identify the component as 'invalid'.
  • 3Corrupted configuration data stored in the SRS control unit (ACU) internal EEPROM. Common causes include vehicle battery disconnection for more than 30 minutes, interrupted software updates, or circuit board corrosion after water ingress.
  • 4Failing to use the dedicated diagnostic tool to perform 'SRS system configuration' or 'ECU coding' after unauthorized repairs causes a hardware and software configuration mismatch.
  • 5Vehicle modifications (such as installing seat covers or non-OEM seats) alter the electrical characteristics of the side airbag circuit, triggering a configuration verification failure.
What To Do
  • 1
    Safety preparation: Set the vehicle to OFF, disconnect the low-voltage battery negative terminal, and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use the BYD VDS2000/2100 diagnostic tool to read the DTC. Confirm B168900 is a current fault (Active), not a history fault. Record the environmental conditions from the freeze frame data.
  • 3
    Location and identification: Refer to the Qin PRO workshop manual wiring diagram to identify the specific airbag component for Circuit 5 (for 2018-2019 Qin PRO models, this is typically the right front seat side airbag SRS-RSAB or right curtain airbag SRS-RCAB).
  • 4
    Visual inspection: Check relevant areas (right front seat, B-pillar, and C-pillar trim panels) for signs of accident repair, water ingress, or disassembly. Check the airbag warning light status.
  • 5
    Connector inspection: Disconnect the SRS ECU and airbag module connectors. Inspect the pins for recession, oxidation, contamination, or mechanical damage. Measure the connector terminal retention force.
  • 6
    Electrical measurement: Use a digital multimeter to measure the resistance of circuit 5 (typical standard value: 2.0-3.0 Ω), check insulation to ground (>1 MΩ), and check for a short circuit to the power supply.
  • 7
    Isolation diagnosis: If resistance is abnormal, connect a 2.7Ω dedicated substitute resistor to the wiring harness. If the fault code changes to open circuit (Open), the airbag module is faulty. If the fault code remains unchanged, the wiring harness is faulty.
  • 8
    Configuration repair: If wiring is normal, use the diagnostic tool to access SRS system special functions. Perform "System Configuration", "VIN Writing", or "Parameter Reset" to ensure configuration data matches vehicle hardware.
  • 9
    Verification test: Clear the fault code, cycle the ignition switch to the ON position, and confirm the self-check passes and the warning lamp turns off. Perform a road test or simulated collision test to confirm the fault does not recur.
Real-World Cases
BYD DTC AI Analysis

Accident repair: SRS not recoded, causing Circuit 5 configuration failure

✓
A 2019 Qin Pro DM had a minor right-front collision. The repair shop replaced the right front seat side airbag. After the repair, the airbag warning light came on. A scan showed DTC B168900 (Loop 5 invalid configuration). The new airbag module measured 2.4Ω resistance (normal), and the wiring harness showed no damage. Further diagnosis found the shop had only replaced the airbag without performing the 'SRS ECU coding' operation using the VDS diagnostic tool. After performing the configuration write procedure and entering the vehicle VIN and airbag configuration parameters, the fault code cleared and the system returned to normal.
BYD DTC AI Analysis

Worn wiring harness under the seat caused intermittent configuration error

✓
2018 Qin Pro petrol variant. Owner reported the airbag light coming on intermittently. Retrieved DTC B168900 (current). Inspection found the protective sheath of the wiring harness under the right front seat had split, and the insulation on two wires had worn through, causing an intermittent short. When the seat moved to a specific position, Circuit 5 resistance momentarily dropped below 0.5 Ω, causing the ECU to flag an 'invalid configuration'. Repaired the harness (replaced the damaged section, reinforced protection). Fault resolved.
BYD DTC AI Analysis

SRS control unit data loss caused a multi-circuit configuration fault.

✓
A 2019 BYD Qin Pro DM had a severely discharged 12V battery (voltage <8V) after being parked for a long time. After battery replacement, the instrument cluster displayed an airbag fault. The scan tool retrieved DTC B168900 and multiple circuit configuration faults. The SRS ECU internal data had been corrupted by the low voltage. When reconfiguration attempts failed, the technician replaced the SRS control unit and performed online matching and coding. This resolved the fault completely.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.