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 8

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.

The B170612 fault code on the Atto 8 indicates a high-severity short to power in the left curtain airbag squib circuit. This can stop the curtain airbag from deploying and may damage the airbag control module, with the SRS warning light staying on. Common causes include worn wiring near the left A-pillar/roof rail or water ingress at the curtain airbag connector. Repair immediately by visiting an authorised dealer. Typical repair cost data is available.
4
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 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 a constant live circuit.
  • 2Seal failure at 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 splicing into the curtain airbag wiring during non-professional modifications (such as installing A-pillar ambient lighting or a dash cam), introducing an external power supply.
  • 4Aging and breakdown of the curtain airbag assembly internal squib insulation layer causes a short circuit between the two squib terminals or to the housing.
  • 5Airbag Control Module (ACM) internal driver MOSFET breakdown, causing the output terminal to remain high (less common)
What To Do
  • 1
    Safety preparation: Turn off the ignition switch, disconnect the negative battery terminal, wait at least 90 seconds (to fully discharge the SRS capacitor), and wear an anti-static wrist strap.
  • 2
    Fault confirmation: Connect the diagnostic tool to read the DTC, confirm B170612 is a current fault (Current), and 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 harness and B+. The resistance must be greater than 10MΩ. Measure continuity to confirm no short to power.
  • 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 is faulty.
  • 6
    Insulation repair: If the wiring harness is damaged, repair using double-layer heat-shrink tubing and re-secure the harness to prevent interference with metal edges. If the connector has water ingress, 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 avoid 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. Confirm the SRS warning lamp turns off after 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 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 overview →
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.