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 3

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.

The B170D1B fault code on the Atto 3 indicates an open circuit in the right curtain shield airbag ignition circuit. Severity is medium because the airbag may not deploy in a side impact or rollover. Common causes include a loose or poorly connected right-side airbag harness plug, or an internal fault in the curtain airbag igniter. The recommended fix is to visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Right curtain airbag wiring harness connector loose or poor contact (typically the yellow plug on the right side of the headliner or at the B-pillar)
  • 2Open circuit damage to the right curtain airbag module internal igniter (broken internal spiral coil or propellant failure causing abnormal resistance)
  • 3Physical damage to the wiring harness (fatigue fracture of the wiring harness inside the B-pillar from frequent door opening and closing, or accidental damage during headliner repair)
  • 4Oxidized or backed-out terminals at the SRS control module (ACU) connector, interrupting communication with the right curtain airbag.
  • 5Water ingress or high humidity causes internal corrosion in the curtain airbag connector, resulting in excessive contact resistance that the system detects as an open circuit.
What To Do
  • 1
    Safety preparation: Disconnect the low-voltage battery negative terminal. 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 interior trim panels. Verify the yellow connector (usually marked 'CSAB RH' or similar) is fully locked. Inspect the terminals for oxidation, burn marks, or signs of water ingress.
  • 3
    Resistance measurement: Disconnect the right curtain airbag connector. Use a multimeter to measure the resistance between the terminals on the curtain airbag side. Normal value: 2.0-5.0 Ω. If the reading is infinity (OL) or >10 Ω, the curtain airbag assembly is damaged. Replace the curtain airbag assembly.
  • 4
    Wiring harness continuity test: Measure the continuity of the two wires between the curtain airbag connector and the SRS ECU (<1 Ω). Measure the insulation resistance to body ground and the 12V power supply (>10 MΩ) to check for intermittent open circuits.
  • 5
    Reset verification: Reconnect all connectors (listen for the locking 'click'), restore power, clear the fault code using VDS or a Launch diagnostic tool, perform the 'SRS system self-check' or 'collision output check', and verify B170D1B does not return and the warning light 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 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.
Common problems reported for Atto 3 →Atto 3 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.