AU
B170612

DTC B170612 indicates the Airbag Control Module (ACM) detects abnormal continuity between the left curtain shield airbag squib circuit and the vehicle power supply (B+) — Qin Plus

Safety System

DTC B170612 indicates the Airbag Control Module (ACM) detects abnormal continuity between the left curtain shield airbag squib circuit and the vehicle power supply (B+).

In the SRS system, the squib remains isolated from the power supply during normal operation.

The ACM provides a brief pulse current only at the moment of deployment.

A short to power continuously energizes the circuit, resulting in the following: (1) The curtain airbag fails to deploy during a collision, resulting in a loss of side protection. (2) Short-circuit current may damage the internal ACM driver circuit. (3) The system enters fault protection mode, continuously illuminates the instrument cluster SRS warning light, and may sound a buzzer on some models.

This fault constitutes a hard short and typically does not clear automatically.

Repair immediately.

4
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Worn wiring harness insulation between the left A-pillar and roof side rail causes the curtain airbag power wire to short to the body 12V power wire or permanent live circuit.
  • 2Seal failure in the left curtain airbag connector (usually located above the A-pillar or inside the headliner) allows water ingress, causing an electrolytic short circuit between the terminals.
  • 3Incorrectly tapping into the curtain airbag wiring during unauthorized modifications (such as installing A-pillar ambient lighting or a dashcam), introducing an external power supply.
  • 4Aging and breakdown of the squib insulation layer inside the curtain airbag assembly causes a short circuit between the two squib terminals or to the housing.
  • 5Airbag Control Module (ACM) internal driver MOSFET breakdown, causing a continuous high state at the output terminal (less common).
What To Do
  • 1
    Safety preparation: Turn off the ignition, disconnect the negative battery terminal, wait at least 90 seconds (allowing the SRS capacitor to discharge fully), and wear an anti-static wrist strap.
  • 2
    Fault confirmation: Connect the diagnostic tool and read DTCs. Confirm B170612 is a Current fault. Record freeze frame data (crash sensor status, voltage values, etc.).
  • 3
    Visual inspection: Remove the left A-pillar trim panel and headliner edge. Inspect the curtain airbag connector (usually yellow) for looseness, water ingress, corrosion, or backed-out pins.
  • 4
    Circuit test: Disconnect the ACM and curtain airbag connectors. Use a multimeter to measure the resistance between the curtain airbag side wiring harness and B+. Resistance must be greater than 10 MΩ. Measure continuity to confirm no short circuit to the power supply.
  • 5
    Component test: Replace the left curtain airbag with a dedicated SRS simulator (or a 2.7Ω resistor). Clear the fault code, power on, and test. If the fault disappears, the curtain airbag itself is faulty.
  • 6
    Insulation repair: If the wiring harness is damaged, repair using double-wall heat-shrink tubing. Re-secure the harness to prevent contact with metal edges. If water entered the connector, clean and apply conductive grease, or replace the wiring harness.
  • 7
    Component replacement: If inspection confirms an internal short circuit in the curtain airbag, replace the left curtain airbag assembly (Note: keep the new part sealed in its packaging until installation to prevent static electricity).
  • 8
    System reset: Connect the battery. Use the diagnostic tool to clear the fault code. Perform the 'SRS system configuration' and 'crash sensor calibration' procedures. Verify the SRS warning lamp turns off after the self-check.
Real-World Cases
BYD DTC AI Analysis

A-pillar wiring harness chafing causing short to power

✓
The SRS warning light suddenly came on while driving a BYD Qin Pro EV. A scan tool retrieved DTC B170612. Removed the left A-pillar trim and found the curtain airbag harness retaining clip had detached. The harness had chafed against the A-pillar metal frame, wearing through the insulation until the internal copper wires contacted the constant-power wire on the body harness. Repaired the damaged harness with double-layer heat-shrink tubing, replaced the retaining clip, and tightened it to the standard torque of 2.5 N·m. This resolved the fault.
BYD DTC AI Analysis

Aftermarket ambient lighting incorrectly connected to curtain airbag wiring

✓
Symptoms: After installing A-pillar ambient lighting, the BYD E2’s SRS warning light remained on after startup, with DTC B170612 logged. Diagnosis: Inspection found the installer had tapped the ambient lighting power feed into the left curtain airbag connector. Improper insulation caused a short circuit between the live wire and the airbag signal line. Repair: Removed the unauthorized modification wiring and restored the factory harness connections. Curtain airbag resistance measured 2.3 Ω (normal). After clearing the fault codes, the system returned to normal.
BYD DTC AI Analysis

Curtain airbag assembly internal squib short circuit

✓
Symptoms: BYD Yuan Plus (Atto 3), no accident history, no modifications. SRS warning light came on after overnight parking; DTC B170612 present intermittently. Diagnosis: Disconnected the curtain airbag connector. Harness side measurement showed no short circuit. Measured the curtain airbag body resistance: only 0.8Ω, unstable. Determined that internal igniter insulation had aged and broken down. Repair: Replaced the left side curtain airbag assembly (P/N: SC2E-5813800). Performed ACM configuration; system self-test passed.
BYD DTC AI Analysis

Roof leak caused connector short circuit

✓
Symptoms: BYD E3 SRS warning light illuminated after heavy rain, with water staining on the headliner. DTC B170612. Diagnosis: Blocked sunroof drain tube caused water to seep into the left curtain airbag connector (located above the B-pillar), resulting in an electrolytic short between terminals. Repair: Cleared the drain tube. Dried the connector (cleaned with anhydrous ethanol then dried with a heat gun on low setting), applied special conductive grease. Fault resolved.
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.