AU
B1740-00

This DTC indicates that during the self-check, the SRS (Supplemental Restraint System) control module detects, through its internal diagnostic circuit, an open circuit in the left rear side airbag (left curtain airbag or seat side airbag) communication line, or the airbag module initialization resistance falls outside the normal range (typically 2 — Qin Plus

Safety System

This DTC indicates that during the self-check, the SRS (Supplemental Restraint System) control module detects, through its internal diagnostic circuit, an open circuit in the left rear side airbag (left curtain airbag or seat side airbag) communication line, or the airbag module initialization resistance falls outside the normal range (typically 2.0-3.0 ohms).

Consequently, the SRS module cannot confirm the physical presence or electrical connection integrity of the airbag, and the system registers the airbag as "not present".

In a collision, this airbag may fail to deploy, disabling side impact protection for the left rear passenger.

Additionally, the SRS system enters fail-safe mode, which may alter the deployment logic of the entire airbag system and illuminate the instrument cluster airbag fault warning lamp.

The B1740-00 fault code on the Qin Plus indicates an open circuit or abnormal resistance in the left rear side airbag circuit, so the SRS module may register the airbag as not present. Severity is medium because this airbag may not deploy in a side impact. Common causes include a loose wiring connector or an internal airbag squib fault. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Loose, disconnected, or poor contact at the left rear side airbag wiring harness connector (common after seat adjustment, B-pillar trim panel removal/installation, or kicks from rear passengers)
  • 2Airbag module internal squib open circuit or abnormal resistance (internal airbag fault or aging)
  • 3Open circuit, short circuit from abrasion, or short to ground in the wiring harness from the SRS module to the left rear airbag (long-term bending at the seat track or B-pillar sill breaks the copper wire).
  • 4SRS control module internal diagnostic circuit fault (outdated software version or damaged hardware sampling circuit)
  • 5The vehicle previously experienced a side impact, wading, or submersion, causing corrosion or water ingress at the airbag connector, or damage to the wiring harness insulation.
What To Do
  • 1
    Use a BYD VDS or dedicated diagnostic tool to read the fault code. Confirm B1740-00 is a current DTC, not a history DTC. Check the voltage and ambient temperature in the freeze frame data.
  • 2
    Disconnect the battery negative terminal and wait at least 90 seconds to discharge the residual charge in the SRS capacitor and prevent accidental airbag deployment.
  • 3
    Locate the left rear side airbag (Qin series: usually inside the left B-pillar trim panel or on the side of the left rear seat). Verify the yellow dedicated connector is fully locked, and inspect the terminals for oxidation, back-out, or deformation.
  • 4
    Use a multimeter to measure the airbag wiring harness continuity: the circuit resistance between the SRS module connector and the airbag connector must be less than 1 ohm, the insulation resistance to ground must be greater than 1 MΩ, and the short-to-power check must read 0V.
  • 5
    Measure the airbag module resistance (via the wiring harness or direct connection). The standard value is 2.0 ± 0.3 ohms. High resistance indicates an open circuit; low resistance indicates a short circuit. If the resistance is abnormal, replace the airbag assembly.
  • 6
    If the wiring harness has an open or short circuit, repair and rewrap it; if the connector is damaged, replace the dedicated yellow airbag connector and verify the locking tab is secure.
  • 7
    Reconnect all connectors and install the battery negative terminal. Use the diagnostic tool to clear the fault code and perform an SRS system self-check. Confirm the fault code does not return and the warning light turns off.
  • 8
    Verify airbag system functionality (use the diagnostic tool to read the live data stream and confirm the left rear side airbag status displays 'Normal' rather than 'Not Present').
Real-World Cases
BYD DTC AI Analysis

Seat adjustment dislodged the airbag connector

✓
A 2017 Qin EV300 had the airbag warning light on steady. Read fault code B1740-00. Inspection found that frequent forward and backward adjustment of the left rear seat by passengers had loosened the side airbag harness connector under the seat. Reconnected the connector and secured the harness clip, then cleared the code. The fault code did not return.
BYD DTC AI Analysis

B-pillar wiring harness wear caused an open circuit.

✓
2018 BYD Qin EV450 had DTC B1740-00. Removed the left rear B-pillar trim panel and found the curtain airbag wiring harness insulation had worn through at the junction between the B-pillar and the body sheet metal. Prolonged vibration had damaged the insulation, and some copper wires were broken, causing an intermittent open circuit. Repaired the harness, added an anti-chafing sleeve, and resolved the fault.
BYD DTC AI Analysis

Corroded airbag connector on water-damaged vehicle

✓
A 2017 Qin 100 drove through water and stored DTC B1740-00. Inspection found mud and water residue inside the left rear side airbag connector (yellow plug); green corrosion on the terminals caused high contact resistance (measured 8.5 ohms). After cleaning the terminals and applying electronic protectant, resistance returned to normal, resolving the fault.
BYD DTC AI Analysis

Internal igniter fault in airbag module

✓
2017 BYD Qin 80 repeatedly set B1740-00. Harness continuity checked normal; connectors OK. Direct resistance measurement at the left rear side airbag module: infinite (open circuit). Determined internal airbag igniter circuit open. Replaced left rear side airbag assembly. System self-test passed.
BYD DTC AI Analysis

SRS module coding error after accident repair

✓
After accident repairs, a Qin EV300 stored DTC B1740-00. A check found the repair shop had replaced the SRS control module but coded it incorrectly. This base model lacks rear side airbags, yet the module had high-spec coding. Recoding and reconfiguring the SRS module cleared the fault code.
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.