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 8

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 8
  • 1Loose or oxidized Circuit 5 wiring harness connector, or backed-out pins (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 corresponding to 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, an interrupted software update, or circuit board corrosion after water ingress.
  • 4Failure to perform 'SRS system configuration' or 'ECU coding' using the dedicated diagnostic tool after unauthorized repairs, resulting in a hardware and software configuration mismatch.
  • 5Vehicle modifications (such as installing seat covers or aftermarket seats) alter the electrical characteristics of the side airbag circuit, triggering a configuration check failure.
What To Do
  • 1
    Safety preparation: Switch 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 DTCs. Confirm B168900 is a current (Active) fault, not a history fault. Record the environmental conditions from the freeze frame data.
  • 3
    Component location: 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 the relevant areas (right front seat, B-pillar, C-pillar trim) for signs of accident repair, water ingress, or removal and installation. Check the airbag warning light status.
  • 5
    Connector inspection: Disconnect the SRS ECU and airbag module connectors. Inspect the pins for push-out, oxidation, contamination, or mechanical damage. Measure the connector terminal retention force.
  • 6
    Electrical measurement: Use a digital multimeter to measure circuit 5 resistance (standard value typically 2.0-3.0 Ω), check insulation to ground (>1 MΩ), and check for a short circuit to power.
  • 7
    Isolation diagnosis: If the 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 persists, the wiring harness is faulty.
  • 8
    Configuration repair: If the wiring is normal, use the diagnostic tool to access the SRS system special functions and execute "System Configuration", "VIN Writing", or "Parameter Reset" to ensure the configuration data matches the 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 and 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 8 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.