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) — Qin Plus

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 Qin Plus indicates a high-severity SRS fault: a short to 12V power in the right knee airbag ignition circuit. This can prevent correct airbag deployment or trigger SRS fail-safe mode, so the vehicle should be repaired immediately. Common causes include damaged under-dash wiring insulation or water/corrosion at the yellow airbag connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Damaged right knee airbag wiring harness or aged insulation contacts a body power wire (such as a constant 12V line), 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, especially after vehicle wading or A/C condensate leakage.
  • 3Wiring harness pinched, retaining clips damaged, or harness protective sleeve chafed during dashboard (IP) removal and repair, causing exposed copper wire to contact the metal frame or power wire.
  • 4Internal short circuit in knee airbag module igniter (very rare; typically results from an internal airbag manufacturing defect or prior severe vibration)
  • 5Internal driver circuit fault in the SRS control unit (ACU), false detection, or actual internal short circuit (rule out wiring harness faults before confirming)
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). Inspect the yellow right knee airbag connector for looseness, water ingress, corrosion, or obvious burn marks.
  • 4
    Circuit measurement: Disconnect the airbag connector. 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. Check interference points between the harness and the dashboard metal bracket, steering column, and air conditioning duct for damage or signs of crushing.
  • 6
    Sectional isolation: If necessary, disconnect intermediate connectors (such as the instrument panel harness to body harness connector). Measure each section to narrow down the fault location 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, clear the fault code, and perform an SRS system self-check (Key Cycle three times). Verify 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 Qin Plus 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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.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 Qin Plus →Qin Plus 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.