AU
B1741

DTC B1741 indicates the Airbag Control Module (ACM) detected a short to ground in the Left Rear Side Airbag squib circuit — Seal U

Safety System

DTC B1741 indicates the Airbag Control Module (ACM) detected a short to ground in the Left Rear Side Airbag squib circuit.

In the SRS system, two wires (high side and low side) connect each airbag inflator to the ACM.

These circuits normally maintain a high-impedance state.

The ACM logs a short to ground when it detects an abnormally low circuit resistance (close to 0Ω) or a voltage drop to ground potential.

This condition causes the following: 1) The airbag system enters fail-safe mode, disabling this airbag and related airbags. 2) The airbag warning light (SRS light) remains illuminated. 3) The airbag fails to deploy during a collision, severely compromising occupant safety. 4) The system may store related fault codes, such as B1740 (airbag not present).

Different vehicle models or model years may define B1741 as a left front window lift switch signal fault in the Left Body Domain Controller (LBDC) system, reflecting the evolution of BYD fault codes across electrical architectures.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Wiring harness mechanical damage: Prolonged bending of the left rear door wiring harness at the door hinge wears through and cracks the insulation. The internal wire contacts the metal door frame, creating a short to ground.
  • 2Connector water ingress and corrosion: Poor sealing of the airbag connector inside the left rear door trim panel creates an electrolyte path between the pins or to ground after car washing, wading, or rainwater leakage, causing a short circuit.
  • 3Airbag module internal fault: Short circuit in the airbag assembly squib, or internal wiring shorted to the metal housing. Manufacturing defects or long-term high-temperature aging usually cause this.
  • 4Improper modification or repair damage: Fixing screws pierce the dedicated yellow SRS wiring harness when installing aftermarket ambient lighting, audio equipment, or window film, or tools accidentally crush the harness when removing or installing the door.
  • 5ACM internal drive circuit fault: A damaged airbag control module internal monitoring circuit falsely reports a short circuit, or an internal power transistor breakdown causes an actual short circuit.
What To Do
  • 1
    Safety preparation and power isolation: Set the vehicle to OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds (120 seconds for some models) to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Visual and physical inspection: Remove the left rear door trim panel. Carefully inspect the yellow SRS wiring harness sleeve at the door hinge for damage. Inspect the airbag connector (typically located at the door-to-body connection or under the seat) for water ingress, corrosion, or deformed pins.
  • 3
    Circuit continuity and insulation measurement: Disconnect the ACM and left rear side airbag connectors. Use a multimeter to measure the resistance between the airbag-side wiring harness and body ground; normal resistance is greater than 1 MΩ. Measure continuity between both ends of the wiring harness to confirm no short to ground. Check the insulation resistance between the wiring harness and body GND.
  • 4
    Component replacement verification: Replace the original airbag module with a known-good airbag simulator (2Ω resistor) or install a known-good jumper harness. Clear the fault code, power on the vehicle, and read the data stream. Observe if the fault code changes or disappears to determine if the fault lies in the wiring harness, the connector, or an internal short circuit in the airbag module.
  • 5
    Targeted repair or replacement: If the wiring harness has a short circuit, repair the damaged section using heat-shrink tubing and rewrap it, then adjust the harness routing to prevent chafing; if the airbag module has an internal short circuit, replace the left rear side airbag assembly; if the ACM is faulty, replace the airbag control module and perform coding configuration.
  • 6
    System verification and testing: Restore all connections, reconnect the battery, power on the vehicle, and confirm the SRS warning lamp turns off after 6 seconds. Use VDS or a dedicated diagnostic tool to perform "SRS system self-check" and "Clear current fault codes", and confirm B1741 does not reappear. Perform "Collision output test" (Output Check/Diagnostic Check) to verify circuit resistance is within the normal range (1.5-3.0Ω).
Real-World Cases
BYD DTC AI Analysis

BYD S7 Left Front Window Switch Signal Fault (B1741 Related Case)

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Symptoms: The left front window switch could not control the other three door windows, and the switch backlight was flashing. The other windows operated normally from their individual switches. Diagnosis: A VDS scan found DTC B1741 stored in the Left Body Domain Controller (LBDC), indicating an abnormal signal from the left front window switch. LIN bus communication was faulty; power and ground to the switch were normal, but signal transmission was intermittent. Resolution: Replaced the left front door window switch assembly and refreshed the LBDC software, resolving the fault.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM Left Front Seat Control Fault (B1741 Related Case)

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Symptoms: The driver's electric seat would not adjust fully rearward, leaving the seat positioned too far forward. The seat memory function also failed. Diagnosis: Checked the seat adjustment motor operation. The motor ran but the position signal was abnormal. Connected VDS and read the left body domain controller, which stored DTC B1741 and related codes. Inspected the wiring harness connectors beneath the seat and found a LIN bus communication fault. Measured the seat position sensor signal voltage; it was abnormal. Resolution: Replaced the driver's seat adjustment switch, repaired the wiring harness connectors under the seat, and relearned the left body domain controller. This cleared the fault.
Original source ↗
BYD DTC AI Analysis

BYD Song Pro Left Domain Controller Communication Fault (B1741-Related Case)

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Symptoms: The light switch could not turn on the lights. The wiper switch was inoperative. All steering wheel buttons were unresponsive. The instrument cluster displayed Lane Departure Limited and Lane Keep Limited warnings. Diagnosis: A full vehicle scan with VDS found the Left Body Domain Controller (LBDC) had lost communication with multiple subsystems. Checked the LBDC power supply and ground circuits – normal. Measured CAN and LIN line voltages and found the LIN line shorted to ground. Disconnected each sub-module under the LBDC one by one; traced the fault to an internal short in the left front door switch assembly. Resolution: Replaced the left front door switch assembly (window lift, mirror adjustment, door lock controls) and the LBDC fuse. Fault fully resolved.
Original source ↗
BYD DTC AI Analysis

BYD Song MAX left rear side airbag wiring harness worn and shorted

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Symptom: The SRS warning light on the instrument panel stayed on constantly. Scanned the vehicle and retrieved DTC B1741 (left rear side airbag short to ground). No collision history. Diagnosis: Removed the left rear door trim panel and inspected the wiring harness routing at the door hinge. Found the yellow SRS-specific harness sheath had cracked, and the internal airbag igniter wire insulation had worn through, contacting the door metal frame. Confirmed continuity to ground with a multimeter. Solution: Repaired the damaged wiring harness using double-layer heat shrink tubing for insulation. Re-secured the harness routing to avoid contact with sharp edges. Cleared the DTC and the SRS warning light went out normally. System returned to normal.
BYD DTC AI Analysis

Water ingress corroded the airbag connector on a BYD Yuan EV.

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Symptoms: After heavy rain, the vehicle displayed B1741 DTC indicating left rear side airbag short to ground. No other abnormalities. Diagnostic Process: Inspected the airbag connector inside the left rear door trim panel and found the seal ring deteriorated and missing. The connector contained obvious water traces and green corrosion. Pins formed a low-resistance path between pins and to ground. Measured airbag module resistance as normal, confirming the fault was on the wiring side. Solution: Thoroughly cleaned the connector contacts, replaced the waterproof seal ring, dried the inside of the wiring harness with compressed air, applied anti-corrosion treatment to the connector, and reinstalled it. This cleared the fault. Recommendation: Check the door drain holes for blockage to prevent further water ingress.
Other Seal U 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: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.