AU
B1737

DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive) — Seal U

Safety System

DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive).

The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω).

If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power.

This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current.

In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Right middle row seat side airbag wiring harness worn or insulation damaged, shorting to a constant power circuit (such as seat heating or adjustment motor power wires).
  • 2Water ingress, corrosion, or terminal deformation at the yellow airbag connector under the seat or inside the B-pillar trim, causing a short circuit between the power supply terminal and the airbag circuit terminal.
  • 3Right middle row side airbag assembly (curtain or seat airbag) internal igniter short circuit to power, typically resulting from an internal manufacturing defect in the airbag module or a previous external impact.
  • 4Mistakenly connecting the airbag wiring harness in parallel with the 12V power supply wire during vehicle modifications (such as adding seat ventilation, heating, or ambient lighting), or damaging the wiring harness during drilling.
  • 5Airbag control module (SRS ECU) internal driver/monitoring circuit fault causing false detection of a short to power in the right middle-row side airbag circuit.
What To Do
  • 1
    Safety preparation: Set the vehicle to OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS backup power capacitor. Do not measure the airbag terminals directly with a multimeter.
  • 2
    Fault confirmation: Use VDS or a BYD dedicated diagnostic tool to read DTC B1737 and freeze frame data. Record parameters such as vehicle speed and temperature at the time of the fault. Confirm the fault is current, not historical.
  • 3
    Visual inspection: Inspect the yellow wiring harness at the right middle-row seat side (if a side airbag label is present), the lower B-pillar trim panel, and near the seat rail for wear, pinching, water stains, or signs of modification.
  • 4
    Connector inspection: Disconnect the right middle-row side airbag connector (typically a yellow plug with a shorting spring clip). Inspect the terminals for ablation, corrosion, or foreign objects causing a short circuit.
  • 5
    Circuit isolation test: Use a multimeter to measure voltage to ground and to power at the airbag harness side (non-airbag end). A 12V reading confirms a short to power. Use the multimeter resistance setting to measure continuity between this circuit and a known power supply harness to locate the short circuit.
  • 6
    Harness routing inspection: Carefully inspect the harness routing from the right middle-row seat to the SRS ECU (usually via the floor harness and B-pillar). Check specifically for harness wear in the seat slide rail movement area and under the door sill trim plate.
  • 7
    Component replacement: If the wiring harness is damaged, repair the insulation or replace the harness; if abnormal voltage or resistance exists between the side airbag assembly terminals after disconnecting the harness, replace the right second-row side airbag assembly; if the wiring harness is normal but the fault persists, consider replacing the SRS ECU.
  • 8
    System verification: After repair, reconnect all connectors (listen for a locking click) and connect the battery. Use the diagnostic tool to clear the fault code and perform an SRS system self-check. Verify B1737 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

BYD Song MAX: Right-hand second-row seat runner chafed the wiring harness, causing a short circuit.

✓
A 2019 Song MAX with 32,000 km on the clock had a steady airbag warning light on the instrument panel. VDS retrieved fault code B1737 (right second-row side airbag short to power), which would not clear. Technicians removed the right second-row seat and found that the seat rails had been rubbing against the wiring harness near the yellow airbag connector underneath, wearing through the insulation. The exposed wire contacted the seat heater constant power wire (always live), creating a short to power. They repaired the damaged harness with heat shrink tubing, rerouted the wiring to clear the seat rail travel area, and added corrugated tubing protection. This resolved the fault.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM: Right second-row side airbag connector shorted due to water ingress after wading

✓
2021 Tang DM. After wading through about 40 cm of water, multiple warning lights came on the dash, with the airbag light staying on constantly. The scan tool showed active fault code B1737. Inspection found wet carpet beneath the right middle-row seat. Disassembling the airbag connector revealed standing water and verdigris inside; the terminals had shorted to power due to water conductivity. Further testing found degraded insulation in the SRS ECU-to-airbag wiring at the floor level. Repair: dried the interior thoroughly, cleaned the connector with electronic cleaner, replaced the wiring harness assembly beneath the right middle-row seat (including the airbag connector), and waterproofed the harness.
Original source ↗
BYD DTC AI Analysis

BYD Yuan EV right middle row side airbag internal igniter short circuit

✓
2019 Yuan EV, 8,000 km, no collision or water ingress history. Airbag warning light suddenly illuminated. Retrieved DTC B1737. Disconnected the right second-row seat side airbag connector. Measured harness side – no short to power. Measured airbag assembly (integrated into seat) resistance between terminals: 0.5 Ω, and detected 12V to the metal bracket. Determined the airbag internal igniter had shorted to power. Root cause: internal manufacturing defect in the airbag assembly or damage during transport/installation. Replaced the right second-row seat side airbag assembly. System returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Qin Pro leather seat modification damaged the airbag wiring harness

✓
2020 BYD Qin petrol. After an aftermarket leather seat upholstery job, the airbag warning light came on immediately at startup. VDS scan revealed DTC B1737. Inspection found that during removal and reinstallation of the right middle-row seat, a tool pierced the side airbag harness on the seat, causing a short between the airbag igniter circuit and the aftermarket seat heating circuit (which was powered from a constant battery tap). Because of the aftermarket work, the dealership refused warranty. Repair: Soldered the damaged airbag harness and sealed the repair with double-layer heat shrink tubing, disconnected the incorrect seat heating power tap, restored the factory wiring routing, and cleared the fault code.
Original source ↗
BYD DTC AI Analysis

BYD Tang SRS ECU internal circuit fault falsely reports DTC B1737

✓
2021 Tang – intermittent airbag warning light. Retrieved DTC: intermittent B1737. Checked right second-row side airbag wiring harness, connectors, and airbag assembly multiple times — found no faults. Wiring insulation intact, no short to power. Measured drive circuit from SRS ECU to airbag per wiring diagram; when fault occurred, ECU output terminal showed 12V abnormally. Determined internal monitoring circuit or driver chip failure in airbag control module causing false short-to-power detection. Replaced SRS ECU (required VIN coding and calibration data reconfiguration). Fault eliminated.
Original source ↗
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.