AU
B1723-00

B1723-00 indicates the Supplemental Restraint System (SRS) detected a short to vehicle power (B+, 12V) in the ignition circuit (squib circuit) of the right knee airbag (passenger-side knee airbag, typically located below the right side of the dashboard) — Atto 8

Safety System

B1723-00 indicates the Supplemental Restraint System (SRS) detected a short to vehicle power (B+, 12V) in the ignition circuit (squib circuit) of the right knee airbag (passenger-side knee airbag, typically located below the right side of the dashboard).

Under normal conditions, the SRS control unit (ACU) maintains a specific voltage across the airbag inflator terminals (typically a 5V or 12V pulse diagnostic voltage), and circuit resistance measures between 2.0 and 3.0 Ω.

When the ACU detects the circuit voltage remains at or near battery voltage (>10V), it identifies a short to power.

This fault can cause: 1) the right knee airbag to fail to deploy properly during a collision; 2) the SRS to enter fail-safe mode, disabling all airbag functions; 3) a potential risk of unintended airbag deployment.

This severe-level fault requires immediate repair.

The B1723-00 fault code on the Atto 8 indicates a high-severity SRS fault: a short to 12V power in the passenger-side right knee airbag ignition circuit. This can stop the airbag from deploying correctly or disable SRS functions. Common causes include damaged wiring under the dashboard or corrosion/water damage at the yellow airbag connector. The vehicle should be inspected and repaired by an authorised dealer immediately. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Damaged right knee airbag wiring harness or aged insulation contacts vehicle power wiring (such as a constant 12V circuit), causing a short circuit. This commonly occurs at the wiring harness pass-through hole under the dashboard or near the steering column.
  • 2Water ingress, corrosion, or terminal deformation at the airbag connector (usually a yellow plug) causes a short circuit between terminals, particularly after vehicle wading or A/C condensate leakage.
  • 3During instrument panel (IP) removal and installation, a pinched wiring harness, damaged retaining clips, or worn harness protective sleeve exposes copper wire, causing contact with the metal frame or power wire.
  • 4Internal short circuit in the knee airbag module igniter (very rare; usually results from an internal manufacturing defect in the airbag or prior severe vibration).
  • 5SRS control unit (ACU) internal driver circuit fault, false detection, or actual internal short circuit (confirm after ruling out wiring harness faults).
What To Do
  • 1
    Safety preparation: Power down the vehicle, disconnect the negative battery terminal, and wait at least 90 seconds to fully discharge the SRS backup capacitor and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use a dedicated BYD diagnostic tool (VDS or ED400) to read fault codes. Confirm B1723-00 is a current fault (Active) and check for accompanying fault codes (e.g., B1722, B1724).
  • 3
    Visual inspection: Remove the right knee trim panel (below the glove box or lower right trim panel) and inspect the yellow connector of the right knee airbag for looseness, water ingress, corrosion, or obvious burn marks.
  • 4
    Circuit measurement: Disconnect the airbag connector and use a multimeter to measure voltage to ground on the wiring harness side (not the airbag side). A 12V reading confirms a short to power. Measure resistance to ground; if the resistance is 0 Ω, locate the short circuit.
  • 5
    Harness inspection: Trace the instrument panel harness (IP Harness) toward the SRS control unit. Inspect interference points between the harness and the dashboard metal bracket, steering column, air conditioning duct, and other components for damage or pinch marks.
  • 6
    Section isolation: Disconnect the intermediate connector if necessary (such as the instrument panel wiring harness to body wiring harness mating connector). Measure in sections to narrow the fault range and determine whether the short circuit is on the airbag module side or the wiring harness side.
  • 7
    Fault repair: Repair the damaged wiring harness (protect with waterproof tape and corrugated conduit) or replace the damaged connector. If the airbag module has an internal short circuit, replace the right knee airbag assembly.
  • 8
    System verification: Restore all connections, reconnect the battery, and clear the fault codes. Perform the SRS system self-test (Key Cycle 3 times). Confirm the fault code does not reappear and the instrument panel airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

Knee airbag connector water ingress short circuit in water-wading vehicle

✓
A 2017 Qin EV300. The owner reported the airbag warning light stayed on constantly. Diagnostic scanning retrieved fault code B1723-00 (right knee airbag short to power). The vehicle had previous water ingress. The right knee airbag connector (beneath the center console) showed visible water stains and green corrosion inside — electrolytic corrosion caused a micro-short between the terminals. After cleaning and blow-drying the connector, the wiring harness measured normal. Replacing the airbag wiring harness connector with a new part resolved the fault. Recommend checking the A/C drain tube for blockages that could cause water leaks.
BYD DTC AI Analysis

Dashboard wiring harness crushed and shorted after accident repair

✓
A 2018 Qin EV450 logged DTC B1723-00 after front collision repairs. Inspection found that during the accident repair involving dashboard removal and reinstallation, the right knee airbag harness was not routed to specification. The instrument panel metal bracket pinched the harness, damaging its insulation and causing internal wires to contact the bracket (ground) and nearby power lines, creating a short circuit. The technician rerouted the harness, repaired the damaged wires (adding insulation sleeving), and installed a protective rubber sleeve between the harness and bracket, clearing the fault.
BYD DTC AI Analysis

Aftermarket dash cam installation caused wiring interference

✓
A 2017 Qin 100 came in with the airbag light on after an aftermarket dashcam was installed and its power tapped. Stored fault codes: B1723-00 and B1722-00 (left knee airbag). Inspection found the installer had bundled the dashcam constant 12V power wire with the knee airbag harness under the centre console, and the cable tie securing the bundle pierced the airbag wire insulation, causing a short to power. The technician separated the harnesses, re-insulated the damaged section, and relocated the power feed to the standard fuse box tap point, which resolved the fault.
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.