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 3

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 3 indicates a medium-severity SRS fault where the driver-side front airbag Stage 2 igniter circuit has near-zero resistance, suggesting a short circuit. Common causes include a worn or damaged clock spring/spiral cable or a short inside the driver airbag module igniter. Have the vehicle checked by an authorised dealer, as airbag operation may be disabled or unsafe. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1The internal conductor in the clock spring (spiral cable) breaks and shorts to ground or 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 duct edge, damaging the insulation and causing a short to ground, especially on vehicles with prior accident repairs or modifications.
  • 4Short circuit caused by water ingress, oxidized or bent pins, or loose terminals at the front SRS connector (yellow waterproof connector); common in vehicles driven through water or operated in high-humidity environments.
  • 5SRS control module (ACU) internal detection circuit fault or damaged sampling resistor, causing 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 if the fault is Active or 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 pinch marks. Check the yellow SRS connector (usually below the steering wheel or behind the airbag module) for water ingress, corrosion, loose connections, 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. Normal value: 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 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 changes in resistance.
  • 6
    Harness continuity and insulation test: Disconnect the SRS control module (ACU) connector. Test the harness between the ECU and the airbag for a short to ground or a short between wires. Carefully inspect the sections routed along the steering column and instrument panel frame. If necessary, use a probe to check for internal wire breaks or shorts to ground.
  • 7
    Component replacement cross-check: If the wiring harness tests normal, use a known-good clock spring or dedicated airbag load simulator to confirm whether the fault is in the external circuit or the internal 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, and perform three ignition cycle self-checks. Confirm B17841A does not return 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 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.