AU
B1730

DTC B1730 indicates the airbag control unit (SRS ECU) detects a resistance of 0 ohms in the left second-row side airbag firing circuit (typically located inside the left B-pillar trim or on the side of the left second-row seat) — Atto 3

Safety System

DTC B1730 indicates the airbag control unit (SRS ECU) detects a resistance of 0 ohms in the left second-row side airbag firing circuit (typically located inside the left B-pillar trim or on the side of the left second-row seat).

This indicates a short to ground in the firing circuit, damaged wiring harness insulation shorting to ground, or an internal short circuit in the airbag module inflator.

This fault forces the SRS system into fail-safe mode, preventing the left second-row side airbag from deploying during a side impact, and continuously illuminates the instrument cluster airbag warning light.

Unlike high resistance (open circuit), a 0-ohm resistance typically means current flows directly to ground without passing through the inflator.

This is a hard short circuit fault and requires immediate repair.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Internal igniter short circuit failure in the left middle row side airbag module (manufacturing defect, or moisture ingress and aging causing an internal bridge wire short circuit)
  • 2Water ingress or bent pins causing poor contact at the airbag wiring harness connector (commonly caused by poor B-pillar trim panel sealing; rainwater seeps in and shorts the connector terminals together or to ground)
  • 3Harness wear causing a short to body ground (frequent seat adjustment, B-pillar trim removal/installation, or modifications pinch the harness and wear through the insulation)
  • 4Improper installation of aftermarket accessories or modifications (e.g., fasteners piercing the wiring harness when installing seat covers or floor coverings, or improper wire splicing when adding seat heating or ventilation equipment)
  • 5SRS control unit internal detection circuit fault (less common; damage to the control unit A/D conversion circuit causes a false 0 resistance reading)
What To Do
  • 1
    Safety preparation: Power down the vehicle, disconnect the negative battery terminal, and wait at least 90 seconds to fully discharge the SRS backup power supply and prevent accidental airbag deployment.
  • 2
    Fault Confirmation: Use VDS or a dedicated diagnostic tool to read the fault code. Verify B1730 is a current fault and does not clear. Record freeze frame data to check vehicle status when the fault occurred.
  • 3
    Visual inspection: Remove the left middle-row B-pillar lower trim panel or seat side cover. Inspect the airbag connector (usually yellow) for water ingress, corrosion, deformed pins, or looseness. Inspect the wiring harness for damage or crush marks.
  • 4
    Resistance measurement: Disconnect the airbag module connector. Use a digital multimeter to measure the resistance between the two terminals on the airbag module side. Normal value: 2.0-3.0Ω. If the resistance is 0Ω or close to 0Ω, replace the airbag module.
  • 5
    Harness insulation check: Disconnect the SRS control unit connector. Measure the resistance between the harness-side airbag circuit and body ground. The resistance must be greater than 1MΩ. If the resistance is too low, inspect the harness section by section, focusing on the harness routing inside the B-pillar trim panel and at the seat slide rail.
  • 6
    Short circuit repair: Upon locating wiring harness damage, repair using heat-shrink tubing or insulating tape. Replace the wiring harness assembly if necessary. Ensure sufficient clearance between the wiring harness and vehicle body metal parts, and install a protective sleeve.
  • 7
    Reassembly verification: Reconnect all connectors (listen for a locking click), reconnect the battery negative terminal, and clear the fault code. Turn the ignition switch to the ON position. Observe whether the instrument cluster airbag warning light turns off after 6 seconds. Perform an SRS system self-diagnosis to confirm no faults exist.
Real-World Cases
BYD DTC AI Analysis

Tang DM left second-row side airbag short circuit after wading through water

✓
Vehicle: 2021 BYD Tang DM. Symptom: The airbag warning light on the dashboard stayed on after the vehicle drove through water. Diagnosis: Connected VDS and retrieved DTC B1730 (current fault). Removed the left B-pillar lower trim panel and found the airbag connector (yellow plug) had visible water stains and verdigris corrosion inside. Resistance between the pins measured 0.2 Ω, forming a short circuit. Further inspection found the B-pillar weatherstrip had perished, letting rainwater in. Solution: Cleaned the connector thoroughly with electronic contact cleaner, dried it with compressed air, and applied conductive grease to prevent corrosion. Replaced the left second-row side airbag module (the old one had moisture damage). Repaired the B-pillar weatherstrip. Road tested for one week with no fault recurrence.
BYD DTC AI Analysis

Seat modification damaged wiring harness on Song MAX

✓
Vehicle: 2019 Song MAX. Symptoms: Airbag warning light came on the day after installing leather seat covers. Diagnosis: Read DTC B1730. Asked the owner and confirmed the recent seat cover installation. Removed and inspected the left middle row seat. Found the metal retaining ring for the seat cover had pierced the side airbag wiring harness, causing the ignition wire to short directly to ground on the seat frame. Repair: Cut out the damaged section and soldered in a replacement length of high-temperature insulated wire (cross-sectional area ≥0.5 mm²). Rewrapped with insulating tape, fitted corrugated tubing for protection, and rerouted the harness clear of the clip position. Cleared the fault codes and the system returned to normal.
BYD DTC AI Analysis

Internal short circuit in a batch of Yuan EV airbag modules

✓
Vehicle: 2019 BYD Yuan EV535. Symptoms: No accident history; airbag warning light suddenly illuminated during normal use. Diagnosis: DTC B1730. Resistance at the airbag module connector measured only 0.8Ω, well below specification (2.0–3.0Ω). With the module disconnected, wiring harness insulation to earth tested normal. Confirmed internal short circuit in the module. This production batch has a common quality defect. Repair: Ordered and replaced the left second-row side airbag module (part number requires VIN verification). After fitting the new module, resistance measured 2.4Ω. Cleared DTC and completed system configuration. Fault fully resolved.
BYD DTC AI Analysis

Qin Pro intermittent short circuit on rough roads

✓
Vehicle: 2020 Qin Pro (petrol) Symptoms: Airbag warning light occasionally illuminated on rough roads; functioned normally on smooth surfaces. Diagnosis: DTC B1730 indicated an intermittent fault. Static resistance measured normal. Flexing the wiring harness to simulate driving conditions revealed an improperly seated airbag connector under the left seat of the middle row. During driving on bumpy roads, the yellow connector housing contacted the body metal bracket, causing an intermittent short to ground. Repair: Re-seated the connector and ensured the locking tab fully engaged. Secured the wiring harness to the seat frame with cable ties to prevent movement. Wrapped insulating tape around the connector housing for added protection. Follow-up: No recurrence after one month.
BYD DTC AI Analysis

Tang II SRS control unit software false alarm

✓
Vehicle: 2021 Tang DM-i. Fault: After accident repair (left rear quarter panel sheet metal work), persistent DTC B1730. Replacing the airbag module did not fix it. Diagnosis: Measured new module resistance at 2.2 Ω (normal). Wiring harness insulation to earth normal. Suspected control unit issue. Checked technical service bulletin – this production batch had a software calibration defect, causing false low-resistance detection in cold temperatures. Solution: Updated SRS control unit software to latest version (V2.1 or above), performed sensor calibration, and cleared fault codes. Fault resolved, no hardware replacement needed.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.