AU
B168800

DTC B168800 indicates the SRS (Supplemental Restraint System) control unit detects invalid configuration parameters in circuit 4 (typically the driver-side seat belt pretensioner circuit) — Atto 8

Safety System

DTC B168800 indicates the SRS (Supplemental Restraint System) control unit detects invalid configuration parameters in circuit 4 (typically the driver-side seat belt pretensioner circuit).

Specifically, the control unit detects the circuit resistance falls outside the standard range (normally 2-3 ohms), or the identified hardware configuration does not match the software calibration.

This constitutes a hard fault in the passive safety system.

During a collision, the corresponding restraint device (seat belt pretensioner or airbag) may fail to deploy, severely compromising occupant protection.

Upon fault detection, the SRS control unit illuminates the instrument cluster airbag warning light and may disable the entire airbag system.

The B168800 fault code on the Atto 8 indicates a medium-severity SRS airbag system error where the driver-side seat belt pretensioner circuit shows invalid configuration parameters or resistance outside the normal range. Common causes include a faulty pretensioner or loose, corroded wiring connections. You should visit an authorised dealer immediately for repair. Typical repair cost data is available based on 5 recorded cases.
5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Driver-side seat belt pretensioner internal open circuit or resistance drift (pretensioner deployed or internal coil damaged)
  • 2Loose or oxidized under-seat pretensioner wiring harness connector, or backed-out terminals, causing excessive contact resistance.
  • 3Long-term chafing of the wiring harness near the seat slide rail causes insulation damage, wire breakage, or intermittent short circuits.
  • 4Internal SRS control unit fault or software calibration error causing abnormal identification of Circuit 4.
  • 5Deployed pretensioner not replaced after accident repairs, or replacement part number does not match vehicle configuration.
What To Do
  • 1
    Use BYD dedicated diagnostic tool VDS2000/VDS3000 to read all fault codes, record freeze frame data, and check for accompanying communication fault codes such as U0151.
  • 2
    Inspect the driver-side seat belt pretensioner for obvious signs of deployment (webbing retraction or housing cracks). Measure the pretensioner resistance (standard value: 2.0-3.0 Ω; if out of range, replace the assembly).
  • 3
    Remove the driver's seat and check the yellow pretensioner connector under the seat (usually on the inner side of the seat rail). Verify the connector is fully locked, clean terminal oxidation using electrical contact cleaner, and check for backed-out terminals.
  • 4
    Inspect the full length of the pretensioner wiring harness down the B-pillar, focusing on seat slide rail interference points and detached harness retaining clips. Repair damaged wires, rewrap the harness, and protect it with abrasion-resistant sleeving.
  • 5
    Measure wiring harness continuity between the pretensioner and the SRS control unit (usually located under the center console or inside the center armrest). Verify no open circuit or short to ground or power.
  • 6
    If the pretensioner has deployed or resistance is infinite, replace the driver-side seat belt assembly (including the pretensioner). Verify the new part number matches the vehicle configuration.
  • 7
    Reconnect all connectors, secure the wiring harness with cable ties to ensure a minimum clearance of 20 mm from the seat slide rail, and reinstall the seat.
  • 8
    Clear the fault code and perform the 'SRS System Calibration' or 'Restraint System Configuration' function (enter the vehicle VIN or select the correct vehicle model configuration). Run the self-check procedure to confirm B168800 no longer appears.
  • 9
    Perform a simulated crash test (using the diagnostic tool 'Airbag Test' function without triggering actual ignition) and confirm Circuit 4 status displays 'Normal' and the instrument warning light turns off.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM seat rail chafed wiring harness, causing open circuit in circuit 4

✓
Symptom: Airbag warning light stays on. Retrieved DTC B168800 (Loop 4 Invalid Configuration). Diagnosis: Measured driver-side pretensioner resistance — open circuit (infinite). Removed seat and found pretensioner harness had been chafing against seat rail over time; insulation worn through, three wires completely severed. Fix: Replaced pretensioner wiring harness assembly, rerouted harness to clear seat rail travel path, fitted dedicated protective sleeve. Fault cleared.
Original source ↗
BYD DTC AI Analysis

Qin Pro petrol – Loose connector causing intermittent fault

✓
Symptoms: Intermittent 'Check SRS System' warning after engine start. DTC B168800 set intermittently. Diagnosis: The pretensioner connector under the seat was not fully seated. Internal terminals showed slight oxidation. Contact resistance fluctuated when the vehicle was shaken. Resolution: Repaired the backed-out terminal pins using a specialised tool, applied conductive paste to improve contact, and reassembled. Repeated testing confirmed the fault did not return.
Original source ↗
BYD DTC AI Analysis

Pretensioner not replaced after accident repair, causing invalid configuration

✓
After the front-end collision repair, the airbag light stayed on and DTC B168800 was stored. The driver-side pretensioner had deployed in the accident (the belt webbing was visibly retracted), but the independent shop that did the repair only cleared the codes without replacing the pretensioner. The pretensioner circuit measured open. I replaced the driver-side seatbelt assembly (including pretensioner), recalibrated the SRS configuration with VDS, cleared the fault codes, and everything returned to normal.
Original source ↗
BYD DTC AI Analysis

Qin PRO DM terminal backed out causing poor contact

✓
Symptoms: The airbag warning light occasionally flickered while driving and cleared after stopping and restarting. Diagnostic process: Performed a harness wiggle test to simulate the fault. The issue reappeared when wiggling the wiring harness under the seat. Removed the connector plug and found the pins inside the pre-tensioner connector had backed out, causing intermittent communication loss with the control unit. Solution: Used a dedicated terminal repair tool to adjust the pin positions so the protrusion height met specifications. Applied conductive paste and reconnected. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Frequent seat adjustments in commercial vehicles caused wiring harness aging.

✓
Symptoms: After 80,000 km, a ride-hailing vehicle's dashboard intermittently displayed an airbag fault, logging DTC B168800. Diagnosis: Given the vehicle's heavy use and frequent seat adjustments, we inspected the wiring harness beneath the seat. We found the pre-tensioner harness severely worn at the seat rail, with insulation damaged on multiple wires and exposed copper causing intermittent shorts. Solution: Replaced the pre-tensioner wiring harness, added three securing points to prevent movement, and fitted corrugated tubing for full protection. This completely resolved the fault.
Original source ↗
Other Atto 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.