AU
B170D1B

This DTC indicates the SRS (Supplemental Restraint System) control module detects an open circuit in the Curtain Shield Airbag RH ignition circuit — Atto 8

Safety System

This DTC indicates the SRS (Supplemental Restraint System) control module detects an open circuit in the Curtain Shield Airbag RH ignition circuit.

Specifically, the ACU (Airbag Control Unit) continuously monitors the circuit resistance of each airbag inflator.

When the Curtain Shield Airbag RH resistance exceeds the normal range (typically >10Ω or infinite), the ACU registers a 'disconnected' state.

This fault prevents the Curtain Shield Airbag RH from deploying during a side impact or rollover, severely compromising occupant head protection, and continuously illuminates the instrument cluster airbag fault warning lamp.

3
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Right-side curtain airbag wiring harness connector loose or poor contact (commonly the yellow plug on the right side of the headliner or B-pillar)
  • 2Right curtain airbag module internal igniter open circuit (broken internal spiral coil or propellant failure causing abnormal resistance)
  • 3Physical damage to the wiring harness (frequent door operation causing fatigue fracture inside the B-pillar, or accidental damage during headliner repairs)
  • 4Oxidation or back-out of the SRS control module (ACU) connector terminals interrupts communication with the right-side curtain airbag.
  • 5Vehicle water ingress or high humidity causes internal corrosion in the curtain airbag connector, resulting in excessive contact resistance that registers as an open circuit.
What To Do
  • 1
    Safety preparation: Disconnect the low-voltage battery negative terminal and wait at least 3 minutes to fully discharge the SRS backup power supply and prevent accidental airbag deployment.
  • 2
    Visual inspection: Remove the right A-pillar, B-pillar, and right roof trim panel. Verify the yellow connector (usually marked 'CSAB RH' or similar) is fully locked. Inspect the terminals for oxidation, burn marks, or water ingress.
  • 3
    Resistance measurement: Disconnect the right curtain airbag connector and use a multimeter to measure the resistance between the terminals on the curtain airbag side. The normal value is 2.0-5.0Ω. If the reading shows infinity (OL) or >10Ω, the curtain airbag is damaged and requires replacement.
  • 4
    Wiring harness continuity test: Measure continuity of the two wires between the curtain airbag connector and the SRS ECU (<1Ω). Measure their insulation to body ground and the 12V power supply (>10MΩ) to troubleshoot intermittent open circuits.
  • 5
    Reset verification: Reconnect all connectors (listen for the locking 'click'), restore power, use VDS or a Launch diagnostic tool to clear the fault code, perform the 'SRS system self-check' or 'collision output check', and verify B170D1B does not return and the warning lamp turns off.
Real-World Cases
BYD DTC AI Analysis

BYD E2 right-side curtain airbag intermittent fault after water wading

✓
A 2019 BYD E2 presented with the SRS warning light illuminated after driving through water during a heavy rain. Scanning revealed fault code B170D1B. Removing the right B-pillar trim showed water stains and green copper corrosion inside the curtain airbag harness connector. The technician cleaned the terminals with electrical contact cleaner, applied conductive protectant, reconnected the plug, and wrapped it with waterproof tape. The technician also checked the drain holes for blockages. The fault cleared following the repair.
BYD DTC AI Analysis

Qin EV curtain airbag not connected after accident repair

✓
A 2019 BYD Qin EV was hit on the right rear. After a third-party shop replaced the right side panel, the airbag warning light came on. Diagnosis found the technician didn't fully insert the yellow curtain airbag connector when fitting the new headliner – it was only pushed in halfway, causing poor contact. Fix: Reseated the connector so the locking tab fully engaged, performed 'Airbag Module Recalibration' under 'Configuration and Settings' with a diagnostic scanner, and cleared the fault codes.
BYD DTC AI Analysis

Chafed E3 wiring harness caused open circuit in right curtain airbag

✓
2020 BYD E3 at 80,000 km: Intermittent airbag warning light and DTC B170D1B. Found the lower B-pillar wiring harness at the door hinge had insulation damage from prolonged friction, the internal wires broken but still making intermittent contact. Repair: cut out the damaged section, soldered in colour-matched high-temperature wire, added corrugated tubing for protection, and rerouted the harness away from metal edges.
Other Atto 8 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.