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) — Seal 6 EV

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 Seal 6 EV indicates a high-severity SRS fault: a short to 12V power in the passenger-side right knee airbag ignition circuit. This can prevent correct airbag deployment, disable airbag functions, or risk unintended deployment. Common causes include damaged under-dash wiring or corrosion/water ingress in the yellow airbag connector. Stop using the vehicle if possible and visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1Damaged right knee airbag wiring harness or aged insulation contacts vehicle power lines (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 in the airbag connector (usually a yellow plug) causes a short circuit between terminals. This frequently occurs after vehicle wading or an A/C condensate leak.
  • 3During instrument panel (IP) removal, installation, or repair, a pinched wiring harness, damaged retaining clips, or worn harness protective sleeve exposes copper wire, causing it to contact the metal frame or power wire.
  • 4Internal short circuit in the knee airbag module igniter (very rare; typically results from an airbag manufacturing defect 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 issues).
What To Do
  • 1
    Safety preparation: Power down the vehicle, disconnect the battery negative 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 glovebox or right lower trim panel) and inspect the right knee airbag yellow connector for looseness, water ingress, corrosion, or obvious burn marks.
  • 4
    Circuit measurement: Disconnect the airbag connector and use a multimeter to measure the voltage to ground on the wiring harness side (not the airbag side). A 12V reading confirms a short to power. Measure the resistance to ground; if the reading is 0 Ω, locate the short circuit.
  • 5
    Harness inspection: Inspect along the instrument panel harness (IP Harness) toward the SRS control unit. Carefully check interference points between the harness and the dashboard metal bracket, steering column, and air conditioning duct for damage or pinch marks.
  • 6
    Sectional isolation: Disconnect intermediate connectors if necessary (such as the instrument panel harness to body harness connector). Measure in sections to narrow down the fault location and confirm 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, clear the fault code, and perform the SRS system self-check (Key Cycle three times). Confirm the fault code does not return 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 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.