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B1712

DTC B1712 indicates the SRS (Supplemental Restraint System) detects a 0 ohm resistance in the right curtain airbag firing circuit (located in the roof side rail, protecting front and rear occupant heads) — Qin Plus

Safety System

DTC B1712 indicates the SRS (Supplemental Restraint System) detects a 0 ohm resistance in the right curtain airbag firing circuit (located in the roof side rail, protecting front and rear occupant heads).

This indicates a hard short circuit in the firing circuit (short to ground or short to power), not an open circuit.

Normal airbag inflator resistance ranges from 2.0-3.0 ohms (typical value approx. 2.3Ω).

A 0 ohm resistance allows current to bypass the inflator bridge wire.

This prevents proper airbag deployment during a collision or creates a major safety risk of unintended deployment.

The SRS ECU continuously monitors all firing circuit impedances in real time using a highly sensitive Wheatstone bridge circuit.

If the ECU detects a resistance below the safety threshold (typically <0.8Ω), it sets this DTC, illuminates the airbag warning light, immediately disables the right curtain airbag and related coordinated protection strategies, and enters safety protection mode.

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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Internal short circuit in the right curtain airbag igniter: Manufacturing defects, prolonged moisture exposure, electrolytic corrosion, or abnormal current surges cause insulation breakdown and a short circuit between the positive and negative terminals of the igniter bridge wire inside the airbag module.
  • 2Wiring harness short to ground or power: Wear, crushing, rodent damage, or improper accident repair damages the insulation on the yellow dedicated wiring harness from the SRS ECU to the right curtain airbag (typically routed along the A-pillar, roof side rail, and C-pillar), causing a short to body metal or a power wire.
  • 3Connector pin short circuit: Bent pins, backed-out pins, corrosion from water ingress, metallic debris, or improper terminal spacing in the curtain airbag connector (located inside the headlining or C-pillar trim) cause direct contact between the positive and negative terminals.
  • 4SRS control module internal fault: Abnormal reference voltage in the ECU internal monitoring circuit, a damaged sampling resistor, or a shorted driver chip causes a false resistance reading of 0.
  • 5Improper repair damage: connecting or disconnecting the curtain airbag connector with the ignition switch ON (IG ON), or failing to use electrostatic protection, causing induced current to damage the igniter; or directly measuring the curtain airbag with a multimeter resistance setting during accident repairs (use a dedicated airbag tester).
What To Do
  • 1
    Safety preparation and power isolation: Set the vehicle to OFF, disconnect the 12V battery negative terminal, and wait at least 90 seconds (some new models require 3-5 minutes) to fully discharge the SRS backup power supply capacitor and prevent accidental airbag deployment and personal injury.
  • 2
    Fault confirmation and freeze frame analysis: Connect the VDS or dedicated diagnostic tool, read the DTC B17112 status (current/history), check the freeze frame data for the recorded resistance value and vehicle status when the fault occurred, and check for accompanying fault codes (such as B1711 left curtain airbag, B1600 series crash sensors, etc.).
  • 3
    Visual and physical inspection: Remove the right A-pillar, B-pillar, and C-pillar trim panels and the edge of the headliner. Carefully inspect the curtain airbag wiring harness along the roof harness for obvious damage, crush marks, water stains, burn marks, or abnormal bending. Verify the connector locks are intact and check for backed-out terminals.
  • 4
    Segmented resistance measurement: Disconnect the dual-stage connector (shorting spring type) between the SRS ECU and the right curtain airbag. First, measure the resistance on the curtain airbag side (normal: 2-3 Ω; if <1 Ω, replace the curtain airbag). Then, measure the harness-side resistance to ground and to power (normal: infinite; if continuity exists, repair the wiring harness).
  • 5
    Harness insulation and continuity test: Use a megohmmeter to measure harness insulation resistance (should be >1MΩ), perform a wiggle test to check for intermittent short circuits, and check the harness shielding (if equipped) for damage causing interference.
  • 6
    Replacement verification (substitution method): If the wiring harness insulation is normal, connect a dedicated airbag simulator (2Ω precision resistor) to the circuit in place of the curtain airbag. If B1712 does not reappear after clearing the fault code, this confirms an internal short circuit fault in the curtain airbag inflator.
  • 7
    Repair and Replacement: Replace the faulty curtain airbag assembly (requires single-use clips and special bolts) or repair the wiring harness (triple protection: soldering, heat-shrink tubing, and corrugated conduit). Route the harness according to the original factory layout, leave sufficient length to prevent stretching, apply conductive grease to the connector, and create a waterproof seal.
  • 8
    System reset and final confirmation: Reconnect all connectors (listen for a click to confirm they are fully seated), connect the battery, use the diagnostic tool to clear fault codes, perform the SRS system self-test (requires 3 ignition cycles or a drive cycle), and confirm the warning light turns off normally and no current fault codes exist.
Real-World Cases
BYD DTC AI Analysis

BYD Yuan EV right-side curtain airbag inflator internal short circuit fault

✓
A 2019 BYD Yuan EV's airbag warning light illuminated on the dashboard while driving. Read the DTCs with VDS and found B1712 (right side curtain airbag resistance 0), with freeze frame data showing 0.1 Ω. Removed the right roof interior trim panel and inspected the curtain airbag connector; no damage or signs of water ingress were found. Disconnected the curtain airbag from the harness and measured the resistance across the igniter with a dedicated airbag tester. It measured 0.2 Ω (normal: 2–3 Ω). Diagnosed as a sintered short circuit in the igniter bridge wire. Replaced the right curtain airbag assembly (part number matched to the vehicle VIN). After reassembly, ran the SRS calibration procedure, and the fault was resolved.
Original source ↗
BYD DTC AI Analysis

Song MAX right side curtain airbag wiring harness chafed and shorted after accident repair

✓
A 2019 Song MAX had a B1712 DTC after a third-party shop repaired right-side collision damage. Inspection found the shop had incorrectly removed and refitted the right C-pillar interior trim. The edge of a metal trim clip pinched the curtain airbag harness, damaging the insulation and causing a short to earth (0 Ω). Further inspection found missing harness retaining clips, allowing the wiring to chafe against the C-pillar metal frame while driving. Repair: Replaced the damaged harness section (from the junction to the airbag), performed a solder repair using the genuine wiring harness Repair Kit, rewrapped with high-temperature fleece tape and PVC corrugated tubing, reinstalled all harness retaining clips, and ensured >25 mm clearance from sharp metal edges. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Tang DM: Water ingress, corrosion, and short circuit in right curtain airbag connector after wading.

✓
A 2021 Tang DM logged fault code B1712 after wading through floodwater during a heavy rainstorm. Removing the right A-pillar trim and front roof headlining revealed the curtain airbag connector (located at the A-pillar-to-roof junction) had a degraded waterproof seal. Water had accumulated inside and the terminals had oxidised and blackened, causing an electrolyte short circuit between the positive and negative terminals (resistance measured at 0.5 Ω). Repair steps: Thoroughly cleaned the connector terminals with electrical contact cleaner and a fibreglass brush; blew out the wiring harness interior with compressed air to dry it; replaced the waterproof seal and connector housing; applied special conductive anti-corrosion paste (not ordinary grease) to the terminal surfaces; and wrapped waterproof tape around the connector. The repair cleared the fault. Check the sunroof drain tubes for blockages; these may have caused the leak.
BYD DTC AI Analysis

Qin Pro SRS ECU erroneously reporting zero resistance fault

✓
A 2020 Qin Pro with no accident history had an intermittent airbag warning light on the dash. The scan tool read DTC B1712 as an intermittent fault. The right side curtain airbag resistance measured normal at 2.4Ω, and the wiring harness insulation was good. The fault occurred mostly in rainy weather. Inspection found the SRS ECU mounted beneath the centre console. A nearby AC evaporator drain pipe leaked, allowing occasional water into the ECU connector. This did not cause a direct short circuit, but it drifted the ECU internal monitoring circuit reference voltage, falsely reporting the curtain airbag resistance as 0Ω. The repair sealed the AC drain pipe, replaced the SRS ECU (requiring programming to match the vehicle immobiliser and VIN), and thoroughly dried the wiring harness connectors. The fault has not returned.
Other Qin Plus 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.