AU
B175B-00

DTC B175B-00 indicates the SRS (Supplemental Restraint System) control unit detects the right rear side airbag igniter circuit resistance (typically located in the right rear seat side or C-pillar trim panel) falls below the manufacturer threshold (normal range: 1 — Atto 8

Safety System

DTC B175B-00 indicates the SRS (Supplemental Restraint System) control unit detects the right rear side airbag igniter circuit resistance (typically located in the right rear seat side or C-pillar trim panel) falls below the manufacturer threshold (normal range: 1.8–3.0 Ω; fault condition: below 1.0 Ω or near 0 Ω).

This constitutes a low-resistance airbag circuit fault, meaning the control unit identifies a short circuit risk (wiring harness short to ground, wire-to-wire short, or internal short within the airbag module).

Consequently, the affected side airbag may fail to deploy during a collision (as the ECU interrupts the trigger signal due to the circuit anomaly) or, in extreme cases, deploy unintentionally.

Simultaneously, the SRS system illuminates the instrument cluster airbag warning light and may disable the entire airbag system to protect occupants.

The B175B-00 fault code on the Atto 8 indicates the SRS control unit has detected low resistance in the right rear side airbag igniter circuit, suggesting a possible short circuit. Severity is medium because the airbag may not deploy correctly or could deploy unexpectedly. Common causes include an internal airbag igniter short or damaged wiring shorting to ground. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Right rear side airbag module internal igniter short circuit: Airbag internal igniter wire resistance is abnormally low due to manufacturing defects, aging, or moisture ingress.
  • 2Wiring harness chafed and shorted to ground: Seat adjustment mechanism, seat belt anchor, or sheet metal edge wears through the wiring harness insulation, shorting the wire to the vehicle body.
  • 3Connector water ingress and corrosion: Vehicle wading, a blocked sunroof drain tube, or aging seals cause water ingress into the lower right B/C-pillar airbag connector (typically located under the seat or at the base of the C-pillar). Electrolytic corrosion between the pins creates a low-resistance path.
  • 4Improper seat modification or repair: When replacing seat covers, installing seat heaters, or adjusting the seat, fixing screws crush the wiring harness or connectors fail to lock fully, causing abnormal terminal contact.
  • 5SRS control unit internal sampling circuit fault: ECU internal A/D converter or monitoring chip failure causes a false low-resistance reading (less common; rule out external wiring before confirming).
What To Do
  • 1
    Safety preparation: Turn off the ignition switch, disconnect the 12V battery negative terminal, and wait at least 3 minutes (or follow the workshop manual to ensure the SRS capacitor fully discharges) to prevent accidental airbag deployment during repair.
  • 2
    Data confirmation: Connect the VDS2000/DiLink diagnostic tool. Enter the SRS system and read the live data stream. Verify the right rear side airbag resistance is below the standard value (record the specific resistance value, such as 0.3Ω or 0.0Ω).
  • 3
    Visual inspection: Remove the right rear seat (if applicable) and lower C-pillar trim panel. Check the airbag wiring harness connector (usually a yellow plug) for looseness, water ingress, pin corrosion, or foreign objects.
  • 4
    Module Isolation Test: Disconnect the right rear side airbag connector, connect a dedicated airbag simulator (resistor, usually 2.0Ω) to the wiring harness side, turn the power on, and read the fault code. If the fault changes to "open circuit" or the resistance is normal, the airbag module is faulty. If the resistance remains too low, the wiring harness or ECU is faulty.
  • 5
    Harness continuity test: Disconnect the airbag module and SRS ECU connectors. Use a multimeter to measure the resistance from the harness terminals to ground (should be >1MΩ) and the resistance between the two harness wires (should be >1MΩ). Check for short circuits.
  • 6
    Wiring harness insulation check: Carefully inspect the wiring harness routing, especially where it passes through the seat frame and floor sheet metal holes. Check the insulation for damage. If necessary, repair the wiring harness and install corrugated conduit for protection.
  • 7
    Component replacement: If testing confirms an internal short circuit in the airbag module, replace the right rear side airbag module; if testing confirms a short circuit in the wiring harness, repair or replace the wiring harness; if testing confirms an ECU fault, replace the SRS control unit and perform coding and matching.
  • 8
    System verification: After repair, clear the fault code. Perform static and dynamic tests (including a simulated crash signal test to verify the system correctly identifies the circuit status). Confirm the airbag warning light turns off normally.
Real-World Cases
BYD DTC AI Analysis

Right rear seat adjuster chafed through wiring harness, causing short circuit

✓
2017 BYD Qin EV300, 80,000 km. Airbag warning light on; DTC B175B-00. Inspection found the right rear seat rail wiring harness rubbing against the seat adjustment mechanism's metal edge. Long-term friction wore through the insulation, exposing two bare wires that contacted and shorted. Repair: Wrapped the damaged section with insulation tape, rerouted the harness, added corrugated tubing, and secured with cable ties to prevent interference with moving parts. Fault cleared.
BYD DTC AI Analysis

C-pillar connector corroded after water wading, causing low resistance

✓
Qin EV450 airbag warning light triggered after wading through heavy rain. Scan tool showed right rear side airbag resistance at 0.8Ω (low). Removed lower right C-pillar airbag connector and found water staining and green copper corrosion inside. Cause: Sunroof drain hose connector deteriorated and detached, letting rainwater run down the A-pillar, across the floor and into the C-pillar. Repair: Cleaned connector pins with electrical contact cleaner, applied conductive protective grease, repaired the drain hose. Cleared fault codes; no recurrence.
BYD DTC AI Analysis

Loose connector after accident repair causes intermittent fault

✓
After repairing a right rear side collision on a Qin 100, the dashboard intermittently displayed an airbag fault. Testing revealed intermittent DTC B175B-00. Inspection found technicians had replaced the right rear side airbag during the accident repair, but the connector locking tab had not fully engaged. Vehicle vibration caused poor terminal contact, with resistance fluctuating between 0.5 and 2.0 Ω. After reseating the connector and confirming the locking tab clicked into place, the data stream showed stable resistance at 2.2 Ω and the fault resolved.
BYD DTC AI Analysis

Airbag module requires replacement due to internal igniter short circuit

✓
A 2018 Qin EV300 showed persistent DTC B175B-00. Disconnected the airbag module and connected a simulator to the harness; the DTC changed to open circuit (normal). Harness insulation to ground measured good. Measured the airbag module resistance separately: 0.2Ω, well below the 2.0Ω standard. Determined the airbag igniter was internally shorted. Replaced the right rear side airbag module (required new mounting bracket and bolts), performed system configuration write, and cleared the fault.
BYD DTC AI Analysis

Aftermarket seat heating pad installation pinched wiring harness

✓
A Qin 80 owner reported an illuminated airbag warning light after installing an aftermarket seat heater. Inspection found that while drilling into the right rear seat foam to route wiring, the installer used screws that were too long, piercing the harness sheath and shorting the airbag harness positive and negative leads. Replaced the damaged harness section (severe internal damage required replacing the entire section). Rerouted the wiring to avoid the heating elements. Fault resolved.
Other Atto 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.