AU
B1742-00

DTC B1742-00 indicates the SRS (airbag) control module detects an abnormally low-resistance short circuit between the Left Rear Side Airbag squib circuit and the vehicle positive power supply (+B, typically 12V battery voltage) — Qin Plus

Safety System

DTC B1742-00 indicates the SRS (airbag) control module detects an abnormally low-resistance short circuit between the Left Rear Side Airbag squib circuit and the vehicle positive power supply (+B, typically 12V battery voltage).

Under normal conditions, high resistance isolates the airbag squib circuit from both power and ground.

The SRS module internal capacitor releases current only at the moment of deployment.

A short to power causes: 1) airbag deployment failure (the power supply bypasses the trigger current); 2) a risk of unintended deployment (if short circuit resistance changes or voltage fluctuates); 3) the SRS system to enter fail-safe mode, disabling all airbag functions.

This fault is a continuous, non-intermittent hard short.

The B1742-00 fault code on the Qin Plus indicates a high-severity SRS airbag fault where the left rear side airbag squib circuit is shorted to positive battery power. This can disable airbag operation or increase the risk of unintended deployment, so driving should be avoided if possible. Common causes include damaged rear seat wiring from seat rail friction or water-related connector corrosion. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Rear seat wiring harness mechanical wear: Long-term friction between the left rear seat fore-and-aft slide rail adjustment mechanism and the floor wiring harness damages the yellow airbag wire insulation. The exposed copper core contacts and short-circuits against body power wires (such as the seat heating power supply wire or 12V constant live wire).
  • 2Connector water ingress and electrolytic corrosion: Water in the rear footwell, high-pressure car washing, or a blocked air conditioning drain hose causes water to seep under the seat. Water accumulates between the pins of the airbag wiring harness connector (usually located under the seat or below the C-pillar), forming an electrolytic conductive path and causing a short circuit between the power and signal terminals.
  • 3Modification damage: Clips, screws, or other fasteners used to install aftermarket full-cover seat covers, leather seats, or rear seat heating pads directly pierce or crush the airbag wiring harness, shorting the internal wires to the power wire.
  • 4Wiring harness retention failure: Original harness retaining clips age and break, causing the harness to sag and contact seat metal slide rails, brackets, or sharp body edges. Vibration damages the insulation, allowing the bare wire to touch live components.
  • 5Internal fault in the SRS control module: Power transistor (IGBT) breakdown in the internal ignition drive circuit or a stuck relay causes the circuit terminal to continuously output battery voltage, triggering a false external short circuit detection.
What To Do
  • 1
    Safe power-down and discharge: Turn off the ignition switch, disconnect the negative battery terminal, and wait at least 90 seconds (some models require 3 minutes) to fully discharge the backup capacitor inside the SRS control module and prevent accidental airbag deployment.
  • 2
    Removal and visual inspection: Remove the left rear seat assembly (cushion and backrest). Remove the lower C-pillar trim panel to expose the left rear side airbag module (usually located on the side of the seat backrest or inside the C-pillar trim panel) and the wiring harness connector. Inspect the wiring harness insulation for damage, scorch marks, or punctures. Inspect the connector for water ingress, oxidation, or deformed pins.
  • 3
    Circuit isolation measurement: Disconnect the SRS control module main harness connector. Use a multimeter to measure the resistance between the left rear side airbag circuit pins and power (+B). Normal resistance is infinity (OL). If the resistance is less than 1 Ω, a short to power exists. Next, disconnect the airbag assembly connector. Measure the harness side and the airbag side separately to determine if the short circuit is in the wiring harness or inside the airbag assembly.
  • 4
    Repair or replace the wiring harness: if the harness is damaged, repair it using layered insulation (inner layer: waterproof tape; outer layer: heat-shrink tubing) and maintain at least 50 mm clearance from adjacent power wires; if the harness lies in the seat slide rail path, reroute it and install wear-resistant corrugated conduit or fabric tape; if the airbag itself has an internal short circuit (very rare; resistance is 0 Ω and the harness is normal), replace the airbag module.
  • 5
    Connector treatment and sealing: If water enters the connector, thoroughly clean the pins with a precision electrical contact cleaner (not a general-purpose cleaner). Blow dry with compressed air, apply conductive grease, and reconnect. Check the connector waterproof sealing ring and replace if necessary. Secure the connector at a high position with cable ties to prevent future water ingress.
  • 6
    System reset and verification: Restore all connections, reinstall the seat, and connect the battery. Use the BYD dedicated diagnostic tool (VDS2000 or Launch X-431) to clear the fault code. Perform an 'SRS system self-check' or 'ignition circuit resistance learning' and confirm B1742-00 does not return. Road test the vehicle, simulate seat adjustments and bumpy road conditions, and verify the fault is resolved.
Real-World Cases
BYD DTC AI Analysis

BYD Qin EV - Rear seat runner chafed through wiring harness

✓
The airbag warning light would illuminate intermittently while driving, and always after rear passengers adjusted their seat position. Technicians removed the left rear seat and found interference between the seat runner and the airbag wiring harness mounting point. Repeated forward and rearward adjustment had chafed through the insulation of the yellow airbag wire, and the exposed copper contacted the 12V power supply wire for the seat heating module, causing a short to power. Stripping back the harness revealed three wear points, one of which had fused to the red wire.
Original source ↗
BYD DTC AI Analysis

BYD Qin EV450 - Rear connector corroded due to water wading

✓
After driving through standing water (depth up to the lower door sill), the airbag warning light on the instrument panel remained on. The scan tool retrieved code B1742-00. Inspection found obvious mud and water traces inside the white 2-pin airbag connector under the left rear seat. Electrolytic corrosion between the pins formed green oxide, reducing resistance between the power and signal pins to 0.5Ω and causing a short to power.
Original source ↗
BYD DTC AI Analysis

BYD Qin 100 - Aftermarket seat cover damaged wiring harness

✓
After the owner fitted full-surround genuine leather seat covers, the airbag warning light immediately came on and stayed on. Inspection found that metal staples securing the covers had pierced the left rear side airbag wiring harness sheath, causing a short between the airbag igniter wire (yellow) and the seat heater power wire (red). A multimeter reading showed 0Ω resistance to the power supply terminal. After removing the staples and repairing the harness, the fault cleared.
Original source ↗
BYD DTC AI Analysis

BYD Qin 80 - Connector locking tab broke, causing the plug to come loose and short out.

✓
The vehicle operated as a ride-share car. Rear passengers frequently kicked the left rear C-pillar area. Inspection found the left rear side airbag connector locking tab fractured, so the connector did not fully latch. On bumpy roads the connector shifted, the pins contacted the adjacent 12V constant power terminal and caused an intermittent short to power. Replaced the connector and re-secured the wiring harness routing. Problem resolved.
Original source ↗
BYD DTC AI Analysis

BYD Qin EV300 - Wiring harness retaining clip aged and detached.

✓
The vehicle is 5 years old. The factory wiring harness retaining clip under the left rear seat had aged and snapped, allowing the harness to sag and contact the seat rail. An aftermarket rear seat heater was installed later; its 12V power cable insulation had worn through and bonded to the OEM airbag harness, causing fault B1742-00. Repair involved reorganising both harnesses, replacing the clip, and separating the high- and low-voltage circuits.
Original source ↗
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.