AU
B175A-00

DTC B175A-00 indicates the Airbag Control Module (ACM) detects 0 ohms resistance in the igniter (inflator) circuit of the right rear side airbag, typically located in the right rear seat side or C-pillar trim panel — Seal U

Safety System

DTC B175A-00 indicates the Airbag Control Module (ACM) detects 0 ohms resistance in the igniter (inflator) circuit of the right rear side airbag, typically located in the right rear seat side or C-pillar trim panel.

Normal igniter resistance is 2.0-3.0 ohms.

A resistance of 0 indicates a short circuit.

Possible causes include an internal igniter short, a wiring harness short to ground, a short between connector terminals, or a control module internal driver circuit fault.

This fault forces the SRS system into fail-safe mode.

The right rear side airbag may fail to deploy during a collision, and the airbag warning lamp (SRS lamp) may illuminate continuously.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Airbag igniter internal short circuit: Moisture, manufacturing defects, or aging caused an internal short circuit in the igniter bridge wire or pyrotechnic charge inside the airbag assembly.
  • 2Harness short circuit: Seat adjustment wear, crushing, water ingress, or rodent chewing damages the wiring harness insulation under the right rear seat or in the C-pillar area, causing a short to ground or a short between twisted pair wires.
  • 3Connector fault: Airbag connector (usually yellow) terminals are bent or backed out, or the shorting bar failed to separate correctly during connection, causing a short circuit between terminals.
  • 4Internal control module fault: Damaged airbag drive circuit inside the SRS ECU triggers a false low-resistance fault.
  • 5Improper repair procedures: Connecting or disconnecting the airbag connector without disconnecting the battery during recent seat or interior trim panel removal or installation, causing static discharge or accidentally triggering a short circuit.
What To Do
  • 1
    Safety preparation: Switch the vehicle OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Locate the component: Confirm the right rear side airbag position (on Qin series models, this is typically located on the side of the right rear seat backrest or inside the lower C-pillar trim panel). Inspect the yellow dedicated connector and wiring harness for damage, water stains, or crush marks.
  • 3
    Isolation measurement: Disconnect the airbag connector (use a dedicated shorting clip to prevent static electricity). Use a digital multimeter to measure the resistance between the terminals of the airbag assembly side connector. Normal resistance is 2.0-3.0Ω. If 0Ω, replace the airbag assembly.
  • 4
    Harness inspection: Measure resistance to ground at the harness-side connector terminals and resistance between terminals. If resistance is 0 Ω or extremely low, inspect the entire harness routing (especially at seat slide rails and hinges). Repair damaged insulation or replace the harness.
  • 5
    Simulation test: Connect a 2.7Ω dedicated simulation resistor (substitute load) to the SRS ECU-side wiring harness. Clear the DTC. If the fault disappears, the original airbag assembly is faulty. If the fault remains, check the SRS ECU or wiring harness for a short to ground.
  • 6
    System reset: After repair, reconnect all connectors (listen for the locking click) and connect the battery. Use the VDS diagnostic tool to clear the fault code and execute the 'SRS system self-learning/configuration' procedure. Confirm DTC B175A-00 does not return and the SRS warning light turns off normally.
Real-World Cases
BYD DTC AI Analysis

Song Pro DM left-hand temperature blend door actuator internal motor open circuit

✓
Symptoms: At 32,000 km, left vent blows hot air with AC on regardless of temperature setting (16°C or 28°C). Right side normal; no warning lights. Diagnosis: VDS showed AC DTC B175A-00 (driver side temperature blend door actuator fault). Disassembly revealed actuator motor resistance infinite (normal 20-50Ω) and internal plastic gear stripped. Repair: Replaced left side temperature blend door actuator assembly (HAC-8107310) and ran blend door initialization.
Original source ↗
BYD DTC AI Analysis

Qin Plus EV temperature blend door actuator binding caused by installation stress

✓
Symptoms: 6-month-old vehicle. Left side of dual-zone climate control has delayed temperature regulation (5-minute cooling-to-heating transition) with clicking noise. Diagnosis: History DTC B175A-00 stored in HVAC system. Disassembly found actuator mounting bracket assembly stress caused misalignment between the output shaft and damper linkage, making the position sensor voltage jump between 0.5V–2.3V instead of sweeping smoothly from 0.5V–4.5V. Repair: Re-adjusted actuator mounting angle to eliminate stress and applied low-temp grease to the linkage.
Original source ↗
BYD DTC AI Analysis

Deformed HVAC housing after accident repairs caused Tang DM-i actuator disconnection

✓
**Symptoms:** Minor right-front impact at 15 km/h. After replacing the front bumper and right fender, the left side blew only cold air — no heat. **Diagnosis:** The collision didn’t touch the AC system, but current DTC B175A-00 was stored. Inspection revealed slight deformation of the HVAC housing: the left temperature blend door actuator mounting bracket had shifted, the output shaft detached from the blend door, and the actuator spun freely. **Resolution:** Adjusted the HVAC housing mounting position, reconnected the actuator to the blend door, manually calibrated the blend door zero position, and ran the AC self-learning procedure.
Original source ↗
BYD DTC AI Analysis

Han EV wiring harness connector oxidation caused intermittent temperature control failure

✓
Symptoms: Intermittent left-side temperature control failure; system recovers after restart. Occurs every 1–2 weeks with panel flickering. Diagnosis: Intermittent history DTC B175A-00. Found green corrosion on B09 connector pins under left dashboard. Actuator supply voltage drops to 9V during fault (normal 12V). Repair: Cleaned B09 connector pins with contact cleaner and conductive protective grease. Added wiring harness retaining clips to prevent vibration.
Original source ↗
BYD DTC AI Analysis

Aftermarket center screen installation on Song Max caused loose connection at actuator connector.

✓
Symptoms: One week after installing an aftermarket centre display, the left-side AC temperature stuck at maximum heat and would not adjust. Fuel consumption increased. Diagnosis: DTC B175A-00. Inspection found the left-side temperature blend door actuator connector loose from dashboard disassembly during the modification. The aftermarket head unit also had a CAN protocol conflict, sending incorrect blend door position commands that stalled the actuator. Repair: Reseated the actuator connector and wrapped it with waterproof tape. Disconnected the aftermarket head unit from the CAN bus, retaining only power and audio/video connections.
Original source ↗
Other Seal U Fault Codes
B1108For 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.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.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.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.
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.