AU
B175212

DTC B175212 indicates the Supplemental Restraint System (SRS) detects abnormal continuity between the ignition circuit of the right rear side airbag (Side Airbag Module, typically installed inside the C-pillar trim panel or on the side of the seat backrest) and the vehicle power supply positive (B+) — Atto 3

Safety System

DTC B175212 indicates the Supplemental Restraint System (SRS) detects abnormal continuity between the ignition circuit of the right rear side airbag (Side Airbag Module, typically installed inside the C-pillar trim panel or on the side of the seat backrest) and the vehicle power supply positive (B+).

In the SRS architecture, the airbag squib circuit must maintain high-resistance isolation from both power and ground.

When the ECU detects that the circuit voltage continuously exceeds the threshold (typically over 80% of supply voltage) and the resistance falls below the specified value (<1kΩ), it identifies a short to power.

This fault may cause: 1) Airbag deployment failure during a collision (ECU triggers protective cut-off). 2) Accidental airbag deployment in extreme cases due to false triggering. 3) SRS fail-safe mode activation, limiting overall vehicle airbag functions.

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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Mechanical damage to the under-seat wiring harness: The right rear seat fore-and-aft adjustment mechanism interferes with the wiring harness mounting point. Prolonged friction damages the insulation, exposing the power wire and causing a short circuit to the vehicle body metal.
  • 2Connector water ingress and corrosion: Vehicle wading, a blocked sunroof drain, or a spilled beverage in the rear causes a short circuit between the terminals of the airbag wiring harness connector at the C-pillar or under the seat (usually where the floor harness connects to the seat harness).
  • 3Airbag module internal fault: High-temperature aging or manufacturing defects damaged the inflator igniter coil insulation, causing a short circuit between the two terminals or to the housing.
  • 4SRS ECU drive circuit fault: MOSFET breakdown in the airbag control unit internal boost circuit causes the ignition pin to continuously output high voltage.
  • 5Improper modification or repair: When installing seat ventilation/heating, replacing seat leather, or removing the C-pillar trim panel, retaining clips pierce the wiring harness, or improper securing causes the wiring harness to deviate from the standard routing.
What To Do
  • 1
    Safe power-down: Turn off the ignition, disconnect the 12V battery negative terminal, and wait at least 90 seconds (120 seconds for some models) to fully discharge the SRS backup capacitor and prevent accidental airbag deployment.
  • 2
    Fault Confirmation and Freeze Frame Analysis: Use the BYD VDS diagnostic tool to read the complete fault codes and freeze frame data. Record vehicle speed, temperature, voltage, and other parameters at the time of the fault to determine if the fault is intermittent.
  • 3
    Visual inspection: Remove the right rear seat (cushion and backrest), lower C-pillar trim panel, and door sill trim panel. Inspect the wiring harness corrugated conduit for damage. Check the connector (usually marked as GJK series or airbag-specific yellow plug) for water ingress, corrosion, or terminal back-out.
  • 4
    Circuit insulation test: Disconnect the airbag module connector (short the harness side using a shorting bar for safety). Use a multimeter to measure the resistance between the harness side and power supply positive (B+). Normal value: >1MΩ. If continuity exists, strip the harness in sections to locate the short circuit.
  • 5
    Airbag module resistance measurement: Measure the resistance between the airbag module terminals. The standard value is 1.5-3.0Ω (varies slightly by model). If the resistance is close to 0Ω or infinite, replace the airbag module.
  • 6
    ECU output verification: Connect the diagnostic tool, enter the SRS system, and perform an active test (output control). Measure the voltage waveform at the ECU output terminal and check for an abnormal continuous high level.
  • 7
    Repair and refit: Repair the damaged wiring harness (use heat-shrink tubing or replace the entire harness section). Maintain at least a 20mm clearance between the harness and the seat slide rail. Use dedicated retaining clips to prevent interference. Apply insulating silicone grease to the connector.
  • 8
    System verification: Restore all connections, connect the battery, and clear the fault codes. Turn the ignition switch to the ON position and verify the SRS warning lamp turns off after the self-check. Perform a simulated crash test (use the diagnostic tool to perform the crash sensor test, not an actual impact) to confirm system function is restored.
Real-World Cases
BYD DTC AI Analysis

Haval H9 front left-centre radar sensor short to power (B190212)

✓
Symptoms: Continuous alarm when radar system activated, dashboard displayed radar fault, DTC B190212 (front left-centre sensor short to power). Diagnosis: Confirmed DTC present after ignition on; removed front left-centre radar sensor and checked surface for damage (none found); measured supply voltage at ECU (12V, normal); checked sensor power pin connections (secure); substituted known-good sensor into faulty vehicle and DTC cleared, confirming internal short in original sensor. Solution: Replaced front left-centre radar sensor, reactivated radar system, cleared DTCs and tested OK.
Original source ↗
BYD DTC AI Analysis

BYD Song DM intermittent stalling while driving (CAN network communication fault)

✓
Symptoms: Vehicle occasionally stalls while driving, restarts normally. Irregular fault frequency, no specific warning light on instrument panel. Diagnosis: Diagnostic scan found VCU not communicating. Checked VCU power and ground circuits — supply fuse F4/9 normal. Measured CAN bus voltage and resistance; found backed-out terminal pin at pins G09-14/15 of GJK14 harness connector, causing CAN-H and CAN-L communication interruption. Backed-out pin caused by loose harness retaining clip allowing long-term vibration to pull on connector. Repair: Repaired backed-out CAN harness terminal, re-crimped and secured harness retaining clip, restoring normal VCU communication.
Original source ↗
BYD DTC AI Analysis

BYD Song DM: Abnormal noise from left B-pillar area (body panel welding defect)

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Symptoms: Metallic squeaking from the left B-pillar area while driving, prominent on bumpy roads, unrelated to vehicle speed. Diagnosis: Opened the left front and rear doors and test drove—the noise persisted, ruling out door hinge and check strap faults. Removed the left B-pillar lower trim panel and seatbelt mounting bolts; noise remained. Removed the driver’s seat; same result. Used a stethoscope to isolate the noise to the lower rear of the B-pillar (three-layer steel plate weld joint). No visible weld cracks, but lightly prying the outer steel plate with a tool produced a friction sound. Confirmed: weld separation between the three layers causing microscopic movement and friction. Solution: Cut sections of red plastic tubing (wear-resistant hose) into pads and inserted them between the three B-pillar steel plates as buffers, eliminating direct metal-to-metal contact. Test drive confirmed the fix.
Original source ↗
BYD DTC AI Analysis

BYD Qin Pro right rear airbag wiring harness rubbing against seat rail, causing short circuit

✓
Symptoms: Airbag warning light intermittently illuminated on rough roads and went out after restart. Scanner showed stored DTC B175212. Diagnosis: Removed right rear seat assembly. Found the under-seat wiring harness retaining clip had detached, leaving the harness hanging above the seat rail. Seat movement caused the rail’s sharp edge to chafe through the harness insulation, shorting the airbag igniter wire (normally routed with power cables in the floor harness) to the body. Measured 0.3Ω to ground. Resolution: Replaced damaged floor harness (or repaired locally), rerouted wiring, and secured it above the seat crossmember with cable ties to keep at least 25mm clearance from the rail. Cleared DTC and drove 50km continuous road test with no recurrence.
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.