AU
B170D-00

This DTC indicates the SRS (Supplemental Restraint System) control module detects a disconnected right side curtain airbag or interrupted communication — Qin Plus

Safety System

This DTC indicates the SRS (Supplemental Restraint System) control module detects a disconnected right side curtain airbag or interrupted communication.

When the ignition switch is ON, the SRS module monitors the airbag inflator circuit resistance (normal range: 2.0-4.0 Ω) to verify the airbag module's presence.

If the SRS module detects an open circuit (infinite resistance), a resistance value exceeding the threshold (>10 Ω), or a loss of communication, it flags the airbag as "not connected".

Potential causes include an open airbag wiring harness, a loose connector, oxidized or corroded terminals, an internal open circuit in the airbag module, or a failed internal diagnostic circuit in the SRS control module.

This fault eliminates right-side head protection during a side impact or rollover.

As a critical passive safety system fault, it requires immediate repair.

5
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Right C-pillar and headliner curtain airbag wiring harness connector loose, not fully seated, or locking mechanism failed (common due to improper reassembly after headliner repair or windshield replacement).
  • 2Airbag wiring harness worn or broken inside the A-pillar, C-pillar, or headliner trim panel (long-term door operation or vibration causes harness bending fatigue and insulation damage).
  • 3Open circuit in right curtain airbag module internal igniter (airbag aging, moisture intrusion, or previous impact opened the internal circuit).
  • 4Oxidation, corrosion, or poor contact at the connector terminals between the SRS control module and the airbag (especially common in water-damaged vehicles or high-humidity environments)
  • 5Failure to install genuine parts after an accident triggered airbag deployment, or use of aftermarket parts or simulators with mismatched resistance.
What To Do
  • 1
    Safety preparation: Set the vehicle to OFF, disconnect the low-voltage battery negative terminal, and wait at least 90 seconds to fully discharge the SRS energy storage capacitor. Wear an anti-static wrist strap to prevent airbag deployment.
  • 2
    Visual inspection: Remove the right A-pillar upper trim panel, C-pillar trim panel, and right edge of the headliner. Inspect the curtain airbag yellow dedicated connector (usually located at the junction of the C-pillar and headliner) to verify it seats securely, the locking tab engages fully, and the wiring harness shows no obvious damage.
  • 3
    Resistance measurement: Disconnect the SRS control module connector, locate the right curtain airbag circuit pins, and measure the circuit resistance. The normal value is 2.0-4.0 Ω. Infinite resistance indicates an open circuit in the wiring harness or airbag. A 0 Ω reading indicates a possible short circuit.
  • 4
    Wiring harness sectional continuity check: If resistance is abnormal, measure wiring harness continuity in sections. Inspect the C-pillar to headliner transition area and wiring harness retaining clips for internal breaks (outer sheath intact but internal copper strands broken).
  • 5
    Airbag module test: After verifying the wiring harness is normal, perform a bridge test using a dedicated airbag substitute resistor (2Ω). If the fault code clears, the airbag module has an internal fault.
  • 6
    Repair and verification: Repair the wiring harness (soldering + heat-shrink tubing) or replace the airbag module. Reconnect all connectors (listen for a locking 'click'). Reconnect the battery. Use the VDS diagnostic tool to clear the fault code and perform the 'SRS system self-check'. Verify B170D-00 does not return and the airbag light turns off.
Real-World Cases
BYD DTC AI Analysis

BYD Qin EV right side curtain airbag connector loose

✓
After starting the vehicle, the airbag warning light on the instrument panel stayed on. Read fault code B170D-00. Removed the right C-pillar trim and headliner edge to inspect. Found the curtain airbag harness yellow connector not fully seated in the socket and the locking clip not engaged. Suspected improper installation during a previous headliner replacement at a repair shop. Re-seated the connector firmly and confirmed the locking mechanism fully engaged. Cleared the fault code; the SRS system self-test passed. Fault resolved.
Original source ↗
BYD DTC AI Analysis

BYD Song PLUS intermittent open circuit in curtain airbag wiring harness

✓
When driving on rough roads, the airbag warning light illuminated intermittently. DTC B170D-00 appeared intermittently, with no faults when stationary. Inspection revealed an improperly secured wiring harness inside the right C-pillar. During door operation or body flex, the harness experienced repeated tension, causing fatigue fractures in the internal copper wires while the outer insulation remained intact. Stripping back the harness revealed multiple broken copper wires. Repaired the harness by soldering and sealing with heat shrink tubing, then re-routed and secured it with cable ties to a rigid body bracket to prevent interference with the door mechanism. A one-week follow-up confirmed the fault did not recur.
Original source ↗
BYD DTC AI Analysis

BYD Tang DM: Internal open circuit in right side curtain airbag module

✓
After powering on the vehicle, the instrument cluster continuously displayed 'Please Check Airbag System'. Read DTC B170D-00 but could not clear it. Disconnected the SRS module and measured infinite resistance in the right curtain airbag circuit, confirming an open circuit fault. Removed the right headlining trim, disconnected the airbag connector, and measured resistance directly across the airbag module terminals – again infinite (normal value 2-3Ω). Diagnosed an internal igniter open circuit in the curtain airbag module. Replaced the right curtain airbag module with a genuine unit. Used VDS to perform ECU configuration and coding. After clearing the fault codes, the system returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD e5 right-side airbag connector water ingress and oxidation

✓
Ride-hailing commercial vehicle, airbag warning light stays on, DTC B170D-00. The vehicle had previously waded through water up to sill height. Removed and inspected the right C-pillar airbag connector, found green copper rust and white oxide crystals on the terminal surfaces, causing excessive contact resistance (measured 15Ω). Cleaned the terminals with electronic contact cleaner, applied special conductive grease to enhance contact, and fitted waterproof tape and a dust boot around the connector. Cleared the DTC; the airbag light went out. A three-month follow-up confirmed the fault had not returned.
Original source ↗
BYD DTC AI Analysis

BYD Han EV: Airbag connector unsecured on new vehicle

✓
One week after taking delivery of the new vehicle, the instrument cluster intermittently displayed ‘Airbag System Fault’. DTC B170D-00 was logged as an intermittent history code. Inspection revealed that although the right-hand curtain airbag connector had been correctly inserted at the factory, the locking tab was not fully pressed down. On rough roads, slight movement could occur, causing signal interruption. Removed and reconnected the connector, ensuring the locking tab fully engaged (audible secondary lock click), applied a small amount of conductive grease to the terminals to prevent fretting corrosion, cleared the DTC, and monitored for one week with no recurrence.
Original source ↗
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.