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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.

3
Cases Logged
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

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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

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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.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: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.