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+) — Atto 3

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 — Atto 3
  • 1Worn wiring harness insulation between the left A-pillar and the roof side rail causes the curtain airbag power wire to short to the body 12V power wire or a constant live circuit.
  • 2Water ingress due to a failed seal at the left curtain airbag connector (usually located above the A-pillar or inside the headliner) causes an electrolytic short circuit between terminals.
  • 3Incorrectly splicing into the curtain airbag circuit during non-professional modifications (such as installing A-pillar ambient lighting or a dash cam), introducing an external power supply.
  • 4Insulation layer aging and breakdown inside the curtain airbag assembly squib 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 level at the output terminal (less common).
What To Do
  • 1
    Safety preparation: Turn off the ignition switch, disconnect the negative battery terminal, wait at least 90 seconds (allowing the SRS capacitor to fully discharge), and wear an anti-static wrist strap.
  • 2
    Fault confirmation: Connect the diagnostic tool and read DTCs. Confirm B170612 is a current fault (Current). Record freeze frame data (crash sensor status, voltage values, etc.).
  • 3
    Visual inspection: Remove the left A-pillar trim panel and headliner edge. Check 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 to power.
  • 5
    Component test: Replace the left curtain airbag with the dedicated SRS simulator (or a 2.7Ω resistor). Clear the fault code, power on, and test. If the fault disappears, the curtain airbag is faulty.
  • 6
    Insulation repair: If the wiring harness is damaged, repair it using double-wall heat-shrink tubing and re-secure the harness to prevent interference with metal edges. If water enters the connector, clean the connector and apply conductive grease, or replace the wiring harness.
  • 7
    Component replacement: After confirming 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 discharge.)
  • 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, and 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 Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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.