AU
B175111

This DTC indicates the Supplemental Restraint System (SRS) detected an abnormally low-resistance connection (short to ground) between the right rear side airbag squib circuit (typically located on the outer side of the right rear seat or inside the C-pillar trim panel) and vehicle chassis ground (GND) — Seal U

Safety System

This DTC indicates the Supplemental Restraint System (SRS) detected an abnormally low-resistance connection (short to ground) between the right rear side airbag squib circuit (typically located on the outer side of the right rear seat or inside the C-pillar trim panel) and vehicle chassis ground (GND).

Under normal conditions, the airbag squib circuit maintains a specific resistance (approximately 2-3Ω).

When the ACU (Airbag Control Unit) detects circuit resistance near 0Ω, it registers a short to ground.

This constitutes a critical safety fault.

The system immediately illuminates the SRS warning lamp and disables the right rear side airbag and related coordinated protection functions to prevent accidental deployment while driving or deployment failure during a collision.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Right rear side airbag wiring harness insulation wear: Long-term chafing of the harness against the seat frame, C-pillar trim panel retaining clips, or door sill trim edges wears through the insulation. Internal wires directly contact the vehicle body metal, causing a short to ground.
  • 2Water ingress and oxidation at the connector under the seat or B/C pillar: A blocked rear sunroof drain tube, poor rear windshield sealing, or water entering the right rear door sill during a car wash causes a short circuit between pins or a short to ground inside the yellow SRS connector.
  • 3Wiring harness fatigue due to frequent seat adjustment: Frequent forward and backward sliding of the right rear seat pinches and excessively bends the airbag wiring harness at the seat rail, breaking the internal copper wire and causing a short to ground.
  • 4Improper repair operations: Fixing screws or clips pierce the airbag wiring harness, causing a short to ground during removal or installation of the right rear seat or C-pillar trim panel, or when laying floor coverings/mats.
  • 5Airbag module internal fault: Right rear side airbag igniter internal bridge wire shorted to housing (very rare; usually sets simultaneous fault codes for other airbags)
What To Do
  • 1
    Safe power-down: Turn off the ignition switch, disconnect the negative battery terminal, and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Locate component: Verify the right rear side airbag installation position (Qin Pro series: typically inside the right rear seat outer backrest or C-pillar). Remove the right rear seat or lower C-pillar trim panel to expose the yellow SRS harness connector.
  • 3
    Visual inspection: Check the wiring harness at the seat rails, C-pillar mounting points, and door sill transitions for signs of pinching, cuts, or wear. Check the connectors for green corrosion, water stains, or deformed pins.
  • 4
    Resistance measurement: Disconnect the airbag control unit (ACU) connector. Use a multimeter to measure the resistance between the right rear side airbag circuit pin and body ground. Normal resistance is infinity (OL). Continuity indicates a short circuit.
  • 5
    Segmented inspection: Measure wiring harness continuity in sections between the seat connector and the ACU. Perform a wiggle test (measure while wiggling the harness) to locate the short circuit. If the wiring harness is normal, use the dedicated load tool substitution method to test the airbag assembly resistance.
  • 6
    Repair procedure: If the wiring harness is damaged, strip back the insulation, solder the break point, and insulate using double-layer heat-shrink tubing. Adjust the harness routing to prevent contact with sharp edges. If water enters the connector, clean and dry thoroughly, apply conductive grease, and replace the waterproof connector if necessary.
  • 7
    System verification: Restore all connections, reinstall the seat, and connect the battery. Use the diagnostic tool to clear the fault code. Perform an SRS system self-check. Confirm DTC B175111 does not return and the instrument cluster airbag warning light turns off. Perform a multi-directional seat adjustment test to verify the fault does not recur.
Real-World Cases
BYD DTC AI Analysis

Right rear seat wiring harness winding mechanism internal break and short circuit

✓
Symptoms: SRS warning light stays on after starting the vehicle. The right rear seat had been adjusted frequently. Diagnosis found current fault code B175111. Removed and inspected the right rear seat. Found the side airbag harness wires had fatigue-fractured inside the winding mechanism (similar to a clock spring) at the junction between the seat back and cushion. The broken ends touched the metal seat frame, causing a short to ground. Repair: Replaced the right rear seat airbag harness assembly (including the winding mechanism). Re-secured the harness routing to ensure no interference throughout the full range of seat adjustment.
BYD DTC AI Analysis

Right rear door sill wiring harness connector corroded due to water ingress

✓
Symptoms: The SRS warning light came on after driving in heavy rain or washing the vehicle, and the right rear floor mat was damp. Diagnostics showed intermittent DTC B175111. Inspection found significant water staining and green corrosion inside the yellow SRS connector behind the right rear sill trim panel, with the connector pins showing continuity to ground. Root cause: The sunroof rear drain hose had detached, allowing water to run down the C-pillar and into the sill. Resolution: Unclogged and secured the drain hose. Removed the connector, cleaned the pins with electronic contact cleaner, dried them, applied silicone grease, and replaced the waterproof seal. Fault resolved.
BYD DTC AI Analysis

Seat rail pinched wiring harness after seat removal and refitting

✓
Symptoms: After replacing the right rear seat cover, the airbag warning light illuminated. Diagnostics retrieved code B175111 which would not clear. Diagnosis: The airbag wiring harness was not properly secured during the repair and got trapped between the seat rail and body. Adjusting the seat caused the metal edge to cut through the harness insulation, shorting the wire to ground. Repair: Released the seat mounting bolts and extracted the crushed harness. Cut out the damaged section, re-soldered and re-insulated the wires. Secured the airbag harness to a safe position on the seat frame using dedicated harness clips.
BYD DTC AI Analysis

Internal drive circuit fault in the airbag control module

✓
Symptoms: Fault persisted after ruling out the wiring harness and airbag components; or multiple airbags simultaneously reported short-to-ground faults after water ingress (e.g., B175111, B175211). Diagnosis: Disconnected the right rear airbag connector. Continuity from the harness to the ACU and insulation to ground both tested normal. Measured abnormally low resistance from the corresponding ACU pin to ground. Determined an internal ACU drive MOSFET or filter capacitor breakdown caused a short circuit. Repair: Replaced the airbag control module, performed online programming and matching (synchronised VIN, immobiliser and tyre pressure data), and completed system calibration.
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.