AU
B17131A

DTC B17131A indicates the RHS Curtain Shield Airbag squib circuit resistance falls below the normal threshold calibrated by the SRS control module (typical standard value: 2 — Seal U

Safety System

DTC B17131A indicates the RHS Curtain Shield Airbag squib circuit resistance falls below the normal threshold calibrated by the SRS control module (typical standard value: 2.0 ± 0.5 Ω).

This fault signifies a partial circuit short, an internal component short, or a wiring insulation failure to ground, dropping circuit resistance below approximately 1.5 Ω.

This condition triggers the airbag system fail-safe mechanism.

Low resistance can prevent proper curtain airbag deployment during a collision, as the short circuit diverts ignition energy.

Furthermore, a severe short circuit increases the risk of unintended deployment.

The SRS typically disables the affected curtain airbag circuit, eliminating occupant head protection during a side impact.

This safety hazard requires immediate repair.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Internal turn-to-turn short circuit in the right-side curtain airbag igniter, or moisture inside the gas generator causing abnormally low resistance.
  • 2Worn or damaged wiring harness insulation inside the A-pillar or C-pillar trim panel contacts the vehicle body metal, causing a short to ground.
  • 3Water ingress, pin corrosion, pin back-out, or short circuit between terminals at the curtain airbag module connector (usually located inside the right roof trim).
  • 4SRS control module internal monitoring circuit fault or abnormal sampling resistor, causing a false low resistance reading.
  • 5During vehicle modifications (such as installing a dash cam, applying window tint, or modifying the audio system), tools pierced or crushed the curtain airbag wiring harness, exposing the wire core and causing a short circuit.
What To Do
  • 1
    Use the BYD VDS2000/VDS3000 diagnostic tool to read all fault codes and freeze frame data. Confirm whether B17131A is a current fault or an intermittent history fault. Record the vehicle status parameters at the time of the fault.
  • 2
    Perform the SRS system safety procedure: disconnect the negative battery terminal and wait at least 90 seconds to ensure the SRS capacitor fully discharges, preventing accidental airbag deployment during repair.
  • 3
    Remove the right A-pillar upper trim panel, right roof trim panel, and C-pillar upper trim panel to expose the curtain airbag module and wiring harness connector (harness markings are usually R_CURTAIN, R_SAB, or R_CAB).
  • 4
    Disconnect the curtain airbag module connector. Use a digital multimeter to measure the resistance directly between the two terminals of the curtain airbag inflator. The standard value is 2.0 ± 0.5 Ω. If the measured value is below 1.5 Ω or close to 0 Ω, replace the right curtain airbag assembly.
  • 5
    If the curtain airbag body resistance is normal, check the wiring harness side: Measure the resistance between one terminal of the curtain airbag circuit and body ground (must be greater than 1 MΩ; a value less than a few hundred ohms indicates a short to ground). Check for a short circuit between the harness wires.
  • 6
    Carefully inspect the wiring harness pass-through holes and retaining clips at the A-pillar, C-pillar, and roof for wear or compression marks. Inspect the connector sealing rings for aging. If necessary, repair the wiring harness (soldering + heat-shrink tubing) or replace the connector.
  • 7
    Reconnect all components and the battery negative terminal. Use the diagnostic tool to clear the fault code. Perform the SRS system self-check (usually by cycling the ignition switch ON-OFF 3 times) and confirm the fault code does not reappear. Perform a road test to verify the fault does not recur during vehicle vibration.
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM: Short circuit in right side curtain airbag circuit causing low resistance

✓
Vehicle: 2018 BYD Qin Pro DM. Symptoms: Airbag warning light on instrument panel stays on. VDS reads DTC B17131A (right curtain airbag resistance below threshold). Measured right curtain airbag circuit resistance at 0.6Ω (well below 2.0Ω spec). Removed right A-pillar trim. Curtain airbag harness insulation had been cut by sharp edges where it passes through the sheet metal hole. Exposed copper wires shorted to ground. Repair: Wrapped the damaged area with insulation tape, added corrugated tubing for protection, rerouted the harness to avoid pinching. Cleared DTC. Resistance returned to 2.2Ω. System normal. Reference: Based on similar BYD Qin airbag wiring fault cases.
Original source ↗
BYD DTC AI Analysis

BYD Qin Pro petrol: Curtain airbag connector water ingress corrosion case

✓
Vehicle: 2019 BYD Qin Pro (Petrol). Symptoms: Airbag warning light illuminated after the vehicle drove through water. The scan tool displayed DTC B17131A (right curtain airbag resistance too low). Inspection of the right C-pillar curtain airbag module connector revealed obvious water stains and green copper corrosion inside the plug, causing abnormal continuity between pins and dropping resistance to 1.2 Ω. Root cause: Poor rear sealing allowed water to enter through the C-pillar while driving through water. Solution: Cleaned the connector terminals, removed corrosion using electronic cleaner, dried the components, then applied conductive grease, and replaced the waterproof seal. Normal resistance restored, fault cleared. Reference: Similar connector fault case — BYD Song Max airbag wiring fault.
Original source ↗
BYD DTC AI Analysis

Qin Pro DM seat adjustment caused curtain airbag wiring harness chafing and short circuit

✓
Vehicle: BYD Qin Pro DM 2019. Symptoms: After frequent seat adjustments, the SRS warning light illuminates intermittently, storing DTC B17131A. Diagnosis: The right side curtain airbag harness passes beneath the B-pillar alongside the seat belt pretensioner harness. As the seat moves fore and aft, friction between the two harnesses wore through the insulation, partially exposing the core wires. The exposed wires contacted the body, reducing the curtain airbag circuit resistance to approximately 1.0 Ω. Action: Replaced the damaged harness section, wrapped it with cloth tape, and re-routed the harness to keep a safe distance from moving seat parts. Result: Fault resolved. Reference: Similar harness wear fault; see BYD Tang DM seat belt pretensioner case.
Original source ↗
BYD DTC AI Analysis

Qin Pro curtain airbag module internal short circuit fault

✓
Vehicle: 2018 BYD Qin PRO. Symptoms: Airbag warning light illuminated intermittently. Scan tool read DTC B17131A, sometimes accompanied by U0151 (lost communication with restraint control module). Checked curtain airbag harness and connectors — all normal. Resistance measurement showed unstable right curtain airbag resistance, fluctuating between 0.5 and 2.0 Ω. Diagnosis: internal igniter short circuit or poor contact in the curtain airbag module. Solution: Replaced the right-side curtain airbag module (required headlining removal). After replacement, resistance stabilised at 2.1 Ω. Cleared fault codes and refreshed SRS control module software, completely eliminating the fault. Reference: See BYD Han EV collision sensor fault case (similar module failure).
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.