AU
B175A

DTC B175A indicates the Right Rear Side Airbag ignition circuit resistance measures 0Ω, indicating a short to ground in the airbag circuit or an internal short circuit in the airbag module — Seal U

Safety System

DTC B175A indicates the Right Rear Side Airbag ignition circuit resistance measures 0Ω, indicating a short to ground in the airbag circuit or an internal short circuit in the airbag module.

Normal airbag inflator resistance ranges between 1.5 and 3.5 ohms (typically 2.0-2.8Ω).

When the SRS control module detects a resistance of 0Ω, it identifies a circuit short fault, immediately disables airbag deployment, and illuminates the instrument panel airbag fault warning lamp.

Due to this fault, the Right Rear Side Airbag may fail to inflate and deploy during a side impact, severely compromising occupant protection.

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

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Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Short to ground caused by chafed SRS wiring harness under the right rear seat: Seat sliding or height adjustment causes the yellow SRS wiring harness under the seat to rub against the metal slide rail or spring. Damaged insulation allows the copper wire to contact the vehicle body ground directly.
  • 2Airbag connector water ingress or short circuit caused by bent pins: The right rear side airbag connector is located on the side of the seat backrest or behind the C-pillar trim panel. Vehicle wading, improper car washing, or rainy seasons allow water to enter the connector, causing a short circuit between the pins. Additionally, disconnecting and reconnecting the connector during seat repairs can bend the pins, causing them to touch.
  • 3Airbag module (gas generator) internal short circuit: An internal short circuit in the airbag igniter bridge wire or damp propellant causes an abnormal drop in resistance. This condition is rare but requires replacing the entire airbag module.
  • 4SRS control module internal detection circuit fault: A damaged resistance detection circuit inside the control module triggers a false short-circuit fault, while the actual wiring and airbag are normal.
  • 5Harness incorrectly secured after seat removal and installation: Failing to clip the SRS harness correctly into the retaining slot after repairing the seat trim or heating pad allows the seat frame to pinch the harness, causing a short circuit.
What To Do
  • 1
    Safety preparation and fault confirmation: Disconnect the negative battery terminal and wait at least 3 minutes. Use the BYD dedicated diagnostic tool VDS or Launch X431 to confirm DTC B175A. Check the resistance value in the freeze frame data (should display 0.0Ω). Check for accompanying SRS fault codes (such as B175B left rear side airbag fault).
  • 2
    Visually inspect the connector: Remove the right rear seat backrest side trim panel or lower C-pillar trim panel. Locate the yellow SRS wiring harness connector (usually equipped with a double-locking mechanism). Check inside the connector for water stains, oxidation, corrosion, or bent or deformed pins. Clean with electrical contact cleaner and blow dry.
  • 3
    Harness continuity test: Disconnect the airbag connector. Use a multimeter to measure the resistance between the harness side (body side) and body ground. The normal reading is infinity (OL). A reading of 0 Ω or close to 0 Ω indicates a short to ground in the harness; continue troubleshooting.
  • 4
    Detailed under-seat wiring harness inspection: Remove the right rear seat assembly and fully open the under-seat wiring harness protective sleeve. Inspect the contact areas between the wiring harness and the seat slide rail, springs, and metal brackets for insulation wear, cuts, or indentations. Repair any damage using heat-shrink tubing and waterproof tape. Reroute the wiring harness and secure it with cable ties to prevent interference with moving parts.
  • 5
    Airbag module resistance measurement: Use a dedicated airbag resistance measuring tool (or a high-impedance multimeter) to measure the resistance of the airbag assembly (gas generator). The normal range is 1.5-3.5 Ω. A reading of 0 Ω or infinitely close to 0 Ω indicates an internal short circuit in the airbag module. Replace the right rear side airbag module. (Note: De-energize the airbag during measurement and use the dedicated resistance measurement mode to prevent accidental deployment.)
  • 6
    SRS control module verification: If the wiring harness and airbag module are normal, suspect an SRS control module fault. Inspect the control module connector (usually located under the centre console or behind the centre armrest box) for looseness. Use an oscilloscope to check the detection signal waveform from the control module. If necessary, replace and recode the SRS control module.
  • 7
    System reset and verification: After completing the repair, reconnect all connectors (listen for an audible click), connect the battery, and clear the fault code. Turn the ignition switch to the ON position and observe the instrument cluster airbag warning light: it should turn off after 6 seconds. Use the diagnostic tool to read the data stream and confirm the right rear side airbag resistance displays within the normal range (1.5-3.5Ω). Finally, perform a seat fore-and-aft sliding test to verify there is no wiring harness interference.
Real-World Cases
BYD DTC AI Analysis

Worn right rear seat wiring harness caused B175A in BYD Tang DM

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Vehicle: 2021 Tang DM. Symptom: Instrument panel airbag warning light stayed on constantly. Read DTC B175A (right rear side airbag resistance: 0Ω). Diagnosis: Removed the right rear seat and found the yellow SRS wiring harness sheath underneath had been cut by the seat slide rail edge, with two internal wires exposed and touching the metal rail to create a short to ground. This line supplies the right rear side airbag. Repair: Cut out the damaged harness section, re-soldered the wires and insulated them with heat-shrink tubing. Rerouted the harness, added protective sleeving and securing clips at wear-prone points, and ensured the harness maintains at least 10mm clearance from the rail. After clearing the DTC, the airbag light went out and the data stream showed resistance had returned to 2.3Ω.
Original source ↗
BYD DTC AI Analysis

BYD Song MAX B175A Fault Code Repair After Water Ingress

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Vehicle: 2019 BYD Song MAX. Symptom: After driving through water, the instrument cluster displayed an airbag fault. The scanner read DTC B175A (right rear side airbag short circuit). Diagnosis: Inspected the airbag connector behind the right rear C-pillar trim and found obvious water staining and green corrosion inside, with a micro-short between pins caused by electrolytic corrosion. The C-pillar seal had degraded, letting water soak the connector during the water crossing. Repair: Cleaned the connector pins with electrical contact cleaner and fine sandpaper, dried them with compressed air, and applied contact protectant. Replaced the C-pillar seal to prevent recurrence. The airbag module was undamaged; cleaning the connector fixed the fault and restored normal resistance.
Original source ↗
BYD DTC AI Analysis

B175A false positive after seat removal and refitting on BYD Qin Pro

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Vehicle: 2020 BYD Qin Pro. Symptom: DTC B175A appeared after replacing the right rear seat leather cover. Diagnosis: Inspected the wiring harness beneath the seat. The SRS harness was not clipped into its retaining slot; the seat frame pinched it instead. This compressed and deformed the insulation without breaking it, causing resistance to drop to 0Ω at specific seat positions. Repair: Rerouted the harness, reinforced the insulation with specialized harness tape, and clipped the SRS harness into the factory retaining clip to ensure adequate clearance from the seat frame. Cleared the DTC and tested by repeatedly adjusting the seat position; the fault did not recur.
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.