AU
B175C-00

DTC B175C-00 indicates the airbag control unit (SRS ECU) detects resistance in the Right Rear Side Airbag ignition circuit above the calibrated threshold — Atto 3

Safety System

DTC B175C-00 indicates the airbag control unit (SRS ECU) detects resistance in the Right Rear Side Airbag ignition circuit above the calibrated threshold.

Normal airbag igniter resistance ranges from 1.6Ω to 2.4Ω (standard value approximately 2.0Ω).

The ECU sets this fault when it detects resistance exceeding approximately 2.8Ω or a high-resistance state in the circuit.

This fault indicates poor contact or a partial open in the ignition circuit, or abnormal internal resistance in the airbag module.

As a functional fault in the passive safety system, it may prevent the side airbag from deploying during a collision.

Because the SRS uses a two-stage diagnostic mechanism, this fault code continuously illuminates the airbag warning lamp and may force the entire airbag system into a downgraded protection mode, even if the vehicle remains drivable.

3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Loose or oxidized right rear seat side airbag wiring harness connector: Frequent seat movement or damp environments increase contact resistance at the connector pins. This is the most common cause of the fault.
  • 2Airbag wiring harness worn or internally broken: Repeated bending of the harness at the seat rail, B-pillar, or door sill trim partially breaks the copper wire without causing a complete open circuit, resulting in abnormally high resistance.
  • 3Airbag igniter internal fault: Aging or poor connection of the igniter resistance wire inside the airbag module causes the resistance value to fall outside the normal range.
  • 4SRS ECU internal detection circuit fault: A faulty sampling resistor or detection circuit inside the control unit incorrectly reads the airbag resistance as too high.
  • 5Water ingress or liquid corrosion: After driving through water, water enters the wiring harness connectors below the right B-pillar or under the seat, causing terminal oxidation and corrosion that creates contact resistance.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 3 minutes to discharge residual charge in the SRS capacitor to prevent accidental airbag deployment. Wear an anti-static wrist strap. Do not measure the airbag directly with a standard multimeter (use a dedicated airbag tester or limit the multimeter current to below 10mA).
  • 2
    Visual inspection: Remove the right rear door sill trim panel and seat side trim panel. Inspect the airbag wiring harness for wear, crushing, or water stains. Check the connector under the seat for looseness and broken locking tabs.
  • 3
    Connector handling: Disconnect the airbag module connector (usually yellow). Inspect the terminals for oxidation, backed-out pins, or deformation. Clean with electrical connector cleaner, apply conductive grease, and verify the locking mechanism is intact.
  • 4
    Resistance measurement: Use a low-current ohmmeter to measure the resistance between the two terminals of the airbag module. Normal resistance is 2.0Ω±0.4Ω. If the resistance exceeds 2.8Ω, replace the airbag module. If the resistance is normal, continue inspecting the wiring harness.
  • 5
    Harness continuity test: Disconnect the SRS ECU and airbag connectors. Measure the resistance between the airbag harness terminal and the corresponding ECU terminal. Resistance must be less than 1Ω. Measure the harness insulation resistance to ground and to power. Resistance must be greater than 1MΩ to rule out a short circuit.
  • 6
    Replacement verification: Perform a substitution test using a known-good airbag module or a dedicated airbag simulator (2Ω resistor). Clear the fault code, set the power mode to ON, wait 20 seconds, and read the fault code. If the fault disappears, the original airbag module is faulty. If the fault persists, check the wiring harness or replace the SRS ECU.
  • 7
    Repair and Verification: After repairing or replacing the faulty wiring harness/connector, reconnect all components and clear the fault code. Perform multiple ignition cycles and a road test to confirm the warning light remains off. Use a diagnostic tool to read the SRS data stream and verify the right rear side airbag resistance is within the normal range.
Real-World Cases
BYD DTC AI Analysis

BYD Qin Pro right rear side airbag connector oxidized, causing high resistance

✓
Symptom: Airbag warning light stays on. Scanner shows DTC B175C-00. No collision history; fault appeared suddenly. Diagnosis: Disconnected the battery and checked the right rear seat side airbag connector. Measured airbag harness terminal resistance to ground: >1MΩ (normal). Voltage to ground: <1V (normal). Measured resistance between K08-2 (Y/B) and K71-17 (harness between airbag module and ECU): >1Ω (abnormal). Found the harness connector inside the right rear sill trim oxidised and loose. Fix: Cleaned the oxidised terminals and applied conductive grease. Re-secured the connector. Cleared the fault codes and cycled the ignition multiple times. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD Song Pro DM rear side airbag wiring harness chafing causing intermittent warning

✓
Symptom: Airbag warning light illuminates intermittently, particularly over rough surfaces. Stored DTC: B175C-00. Diagnosis: Found the RH rear seat side airbag connector not fully locked. Reconnected and cleared the DTC, but the fault returned two days later. Further inspection revealed chafing damage to the harness at the seat rail, causing intermittent high resistance. Measuring resistance at the airbag module while moving the harness showed fluctuation between 2.8Ω and 5.2Ω (specification: 2Ω±0.4Ω). Resolution: Replaced the RH rear seat side airbag wiring harness assembly. Adjusted the harness routing to avoid the seat rail and secured it with cable ties, ensuring adequate movement allowance. Cleared the DTCs and road tested; no recurrence.
Original source ↗
BYD DTC AI Analysis

Replaced right rear side airbag on BYD Tang II; fault persists

✓
Symptoms: Airbag warning light stayed on with DTC B175C-00 after right rear door body repair and removal of right rear seat. Shop replaced right rear side airbag module but fault remained. Diagnosis: New airbag module resistance measured 2.1Ω (normal). Checked harness between airbag ECU and module: K08-1 (Y/R) to K71-18 measured 0.8Ω (normal), but K08-2 (Y/B) to K71-17 measured 3.5Ω (high). Found right B-pillar lower connector had water ingress during previous repair, causing pin oxidation. Resolution: Replaced right B-pillar lower SRS harness connector, dried harness and applied waterproof sealant. Reconnected, cleared codes, and cycled ignition multiple times to confirm fix.
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.