AU
B175B1A

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

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 Seal U indicates low resistance in the right rear side airbag igniter circuit, often meaning a short circuit. This is a medium-severity SRS fault because the airbag may not deploy correctly, or could behave unpredictably. Common causes include a shorted airbag module or damaged wiring near the seat rails or C-pillar. Have an authorised dealer inspect and repair it. Typical repair cost data is available.
2
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Right rear side airbag module internal igniter short circuit (internal bridgewire short circuit or moisture ingress)
  • 2Harness wear causing a short to ground (commonly from a pinched or chafed harness near the seat rails or inside the C-pillar trim)
  • 3Connector water ingress or terminal corrosion (vehicle wading, rear floor water ingress, or moisture intrusion into the connector after a car wash)
  • 4SRS control unit internal detection circuit fault (faulty 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) for looseness, backed-out pins, signs of water ingress, or white corrosion. Clean the connector and apply conductive grease 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. A reading close to 0 Ω or <1 Ω confirms a short circuit in the wiring.
  • 5
    Check the wiring harness in sections: disconnect and measure the circuit from the ECU to the airbag. Focus inspection on the wiring harness at the seat rail mounting points, inside the B-pillar trim panel, and inside the C-pillar trim panel for wear, insulation damage, crushing, or 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 (wrap the wiring harness, replace the connector) or replace the faulty airbag module. Verify all connections are secure to prevent poor contact.
  • 8
    Reconnect the battery, clear the fault code, perform the SRS system self-test (turn the ignition switch ON and observe if 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 Seal U Fault Codes
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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.