AU
B175B1A

DTC B175B1A indicates the right rear side airbag igniter circuit resistance falls below the normal ECU threshold (typically below 1 — Atto 3

Safety System

DTC B175B1A indicates the right rear side airbag igniter circuit resistance falls below the normal ECU threshold (typically below 1.0 Ω).

In the BYD SRS (Supplemental Restraint System), standard airbag igniter resistance is generally 2.0–3.0 Ω.

If the ECU continuously detects abnormally low circuit resistance, it logs a short circuit fault (indicating a possible short to ground or internal igniter short circuit).

This fault causes the following: 1) The airbag may fail to deploy during a collision, resulting in a loss of side protection. 2) The airbag may deploy unexpectedly in extreme cases. 3) The SRS enters fail-safe mode and illuminates the airbag warning light.

Common causes include wiring harness wear, connector water ingress, or an internal airbag module short circuit.

The B175B1A fault code on the Atto 3 indicates low resistance in the right rear side airbag igniter circuit, suggesting a possible short circuit. This is a medium-severity SRS fault because the airbag may not deploy correctly, or could behave unpredictably. Common causes include an internal short in the airbag module or damaged wiring near the seat rail or C-pillar. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
2
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Right rear side airbag module internal igniter short circuit (internal bridge wire short circuit or moisture ingress)
  • 2Harness wear causing a short to ground (commonly due to a pinched or chafed harness near the seat rail or inside the C-pillar trim)
  • 3Connector water ingress or terminal corrosion (vehicle wading, rear floor water ingress, or moisture entering connector after car wash)
  • 4Internal fault in SRS control unit detection circuit (abnormal ECU sampling resistor or detection chip)
  • 5Wiring harness damaged during modification or repair (e.g., piercing the harness when installing seat heaters or retrofitting leather seats)
What To Do
  • 1
    Use the BYD VDS diagnostic tool to read fault codes, confirm B175B1A is a Current fault, record freeze frame data, and check for accompanying SRS fault codes (such as B175C).
  • 2
    Perform the safe power-down procedure: disconnect the battery negative terminal and wait at least 3 minutes to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 3
    Check the right rear side airbag wiring harness connector (usually located below the C-pillar or on the side of the rear seat): inspect for looseness, backed-out pins, water ingress, or white corrosion. Clean and apply conductive paste if necessary.
  • 4
    Disconnect the SRS ECU connector (located under the centre console or in the front compartment). Use a multimeter to measure the resistance at the right rear side airbag wiring harness terminal. Normal resistance is 2-3 Ω. Readings close to 0 Ω or <1 Ω confirm a short circuit.
  • 5
    Troubleshoot the wiring harness in sections: disconnect and measure the circuit from the ECU to the airbag. Inspect the wiring harness at the seat rail mounting points, inside the B-pillar trim panel, and inside the C-pillar trim panel for abrasion, damaged insulation, or crushing deformation.
  • 6
    Remove the right rear side airbag module (requires removing the C-pillar trim panel or seat backrest) and directly measure the resistance across the two terminals of the airbag module. If the resistance is <1Ω, replace the airbag module.
  • 7
    Repair the short circuit (tape the wiring harness, replace the connector) or replace the faulty airbag module. Secure all connections to prevent poor contact.
  • 8
    Reconnect the battery, clear the fault code, perform the SRS system self-check (turn the ignition switch ON and verify the airbag warning light turns off after 6 seconds), and perform a road test to verify.
Real-World Cases
BYD DTC AI Analysis

Steering wheel cruise control switch failure (B17 series reference)

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Symptoms: Steering wheel cruise control switch completely inoperative. Pressing the 'Set' button gets no response, and the instrument cluster shows no cruise setting information. Some owners reported abnormal instrument cluster warnings. Diagnosis: The owner replaced the steering wheel cruise control switch assembly, instrument panel relay assembly, and instrument cluster assembly one by one, but the fault remained. Technicians suspected either a faulty Set button or an internal break in the steering wheel clock spring wiring, blocking the switch signal from reaching the BCM. Solution: The forum post did not record a final confirmed solution. Follow-up posts suggested checking the steering wheel clock spring ribbon cable, multifunction switch connectors, and Body Control Module (BCM) software version. Note: Although this is not a direct B175B1A case, it demonstrates the wiring troubleshooting approach for B17-series fault codes.
Original source ↗
BYD DTC AI Analysis

VCU communication interrupted (pin backed out)

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**Symptoms:** Scan tool cannot communicate with the Vehicle Control Unit (VBU/VCU). Some electronic functions failed and the instrument cluster may display "Check Power System" or related warning lights. **Diagnosis:** Technician checked power, ground and CAN bus communication. Found pins G09-14/15 (GJK14 harness junction) backed out, breaking the communication signal. Confirmed fuse F4/9 had not blown, ruling out power supply problems. **Repair:** Fixed the backed-out pins in the wiring harness connector and re-secured the terminals for proper contact. Cleared DTCs with the scan tool. VCU communication returned to normal. **Note:** This case shows a system failure caused by wiring harness connector pin retraction in BYD vehicles. Useful reference for troubleshooting poor harness connections in SRS systems.
Original source ↗
Other Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.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.
Common problems reported for Atto 3 →Atto 3 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.