AU
B17841A

This fault code indicates the SRS control module detects the driver-side front airbag Stage 2 igniter (inflator) circuit resistance at or near 0 ohms, indicating a short circuit (short to ground or short between wires) — Atto 8

Safety System

This fault code indicates the SRS control module detects the driver-side front airbag Stage 2 igniter (inflator) circuit resistance at or near 0 ohms, indicating a short circuit (short to ground or short between wires).

In dual-stage airbag systems, Stage 2 typically provides additional inflation capacity during severe collisions or delays inflation to optimize protection.

A resistance of 0 ohms causes the SRS ECU to determine the igniter circuit is abnormal.

The ECU disables the deployment function of this airbag stage and illuminates the airbag warning light.

In extreme cases, an unstable short circuit creates a risk of unintended airbag deployment, or the airbag stage may fail to inflate normally during an actual collision, reducing protection and severely compromising occupant safety.

The B17841A fault code on the Atto 8 indicates the SRS module detects near-zero resistance in the driver front airbag Stage 2 igniter circuit, usually from a short to ground or between wires. Severity is medium because airbag performance may be reduced and the warning light will stay on. Common causes include a damaged clock spring or a shorted driver airbag module igniter. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Atto 8
  • 1The internal conductor in the clock spring (spiral cable/Clock Spring) breaks and shorts to ground, or shorts between windings. Fatigue damage from frequent steering wheel rotation or long-term wear commonly causes this.
  • 2Short circuit in the driver airbag module (DAB) second-stage igniter generator. Possible causes: manufacturing defect, long-term vibration causing the internal bridge wire to contact the housing, or internal corrosion after water ingress.
  • 3Airbag wiring harness chafes at the steering column, dashboard frame, or wiring channel edges. Damaged insulation causes a short to ground, especially on vehicles with previous accident repairs or modifications.
  • 4Short circuit caused by water ingress, oxidized or bent pins, or loose terminals at the front-row SRS connector (yellow waterproof connector). This commonly occurs in vehicles driven through water or operated in high-humidity environments.
  • 5SRS control module (ACU) internal detection circuit fault or damaged sampling resistor triggers a false short circuit fault (actual external circuit resistance is normal).
What To Do
  • 1
    Safe power-down: Turn off the ignition switch, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS backup power supply and prevent accidental airbag deployment and personal injury during repair.
  • 2
    Fault confirmation and freeze frame analysis: Connect the BYD VDS or dedicated diagnostic tool to read the freeze frame data for DTC B17841A. Confirm whether the fault is currently present (Active) or historical (History). Record key information such as vehicle speed and collision signal status at the time of the fault.
  • 3
    Visual and connector inspection: Check the SRS wiring harness below the steering wheel and inside the dashboard for damage or crush marks. Check the yellow SRS connector (usually located below the steering wheel or behind the airbag module) for water ingress, corrosion, looseness, or bent pins.
  • 4
    Airbag module isolation test: Carefully disconnect the driver airbag module connector (usually a yellow 2-pin or 4-pin connector). Use a dedicated shorting bar or digital multimeter to measure the resistance between the second-stage igniter pins. The normal value is 1.8-3.2 Ω. Measure the resistance between each pin and body ground; the value must be infinite (OL).
  • 5
    Clock spring (spiral cable) test: Disconnect the original clock spring from the airbag module. Measure the harness resistance and insulation to ground at the lower side of the clock spring (towards the SRS ECU). While slowly turning the steering wheel from lock to lock, check for intermittent short circuits or sudden resistance changes.
  • 6
    Harness continuity and insulation test: Disconnect the SRS control module (ACU) connector. Test the harness between the ECU and the airbag for shorts to ground or shorts between wires. Inspect the sections routed along the steering column and instrument panel frame. If necessary, use a probe to check for internal harness breaks or shorts to ground.
  • 7
    Component replacement cross-check: If the wiring harness tests normal, cross-check using a known-good clock spring or a dedicated airbag load simulator to confirm whether the fault is in the external circuit or internal to the SRS ECU (never use a multimeter resistance setting to directly measure an unknown airbag module).
  • 8
    System Repair and Verification: After replacing the faulty component, fully engage all SRS connector locking tabs (listen for two clicks). Reconnect the battery, clear the fault code, perform a self-check for three ignition cycles, and confirm B17841A does not reappear and the airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

BYD Qin EV clock spring internal wear causing short circuit

✓
The instrument cluster airbag warning light stays on. VDS reads active fault code B17841A. Disconnected the driver airbag module; the second stage igniter resistance measured normal at 2.1Ω. Further testing showed the clock spring's second stage igniter circuit resistance to ground drops to 0.3Ω when the steering wheel is at full right lock. Disassembled the clock spring and found the internal flat cable insulation worn at the winding center; copper foil contacting the metal housing caused an intermittent short. Replaced the OEM clock spring (part number must match the VIN). Fault resolved and system self-test passed.
BYD DTC AI Analysis

E2 model: Internal short circuit in airbag module igniter

✓
After driving through water, DTC B17841A set and would not clear. Clock spring wiring harness insulation checked good; found no shorts. Direct measurement between the driver airbag module Stage 2 igniter pin and metal housing read 0Ω, confirming internal seal failure in the airbag module and a short to ground between the igniter bridge wire and housing. Replaced the driver airbag assembly (includes gas generator and cushion—note Stage 1 and Stage 2 igniter pin definitions). Cleared the DTC and performed a simulated crash test; system functions normally.
BYD DTC AI Analysis

Dashboard wiring harness chafing caused intermittent SRS short circuit

✓
The BYD E3's airbag warning light came on intermittently when driving on rough roads. The scanner showed intermittent fault code B17841A. Disassembly revealed that a dashcam mounting screw had pierced the SRS harness corrugated tube on the instrument panel frame, causing the stage-2 airbag harness copper core to contact the metal frame. Repaired the insulation with high-temp insulation tape and fresh corrugated tube, rerouted the harness to avoid sharp metal edges. Fault eliminated.
BYD DTC AI Analysis

False positive fault in SRS ECU internal sampling circuit

✓
The vehicle had no collision history when DTC B17841A suddenly appeared. Replaced the clock spring and airbag module; fault persisted. Oscilloscope check of the SRS ECU igniter detection pulse waveform revealed internal sampling circuit reference voltage drift, causing the ECU to misjudge normal 2.0Ω resistance as 0Ω short. Replaced the airbag control module (ACU), recoded the vehicle configuration, and calibrated the crash sensors. The system returned to normal and the fault code did not reappear.
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.