AU
B161111

DTC B161111 indicates a short to ground in the front passenger airbag (PAB) ignition circuit — Atto 3

Safety System

DTC B161111 indicates a short to ground in the front passenger airbag (PAB) ignition circuit.

In the BYD SRS (airbag) system architecture, this DTC sets when the airbag control unit (ACU) detects the resistance between the front passenger airbag ignition wiring and body ground falls below the calibrated threshold (usually < 2Ω).

This constitutes a hard fault in the active safety system, indicating compromised airbag circuit integrity.

Potential risks include: 1) the front passenger airbag fails to deploy during a collision, resulting in a loss of occupant protection; 2) abnormal wiring causes unintended airbag deployment in extreme cases.

This latch-type fault (Latch DTC) requires a VDS or dedicated diagnostic tool to clear.

It continuously illuminates the instrument cluster SRS warning lamp (solid, not flashing).

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Short circuit between conductor layers inside the clock spring (spiral cable): The front passenger airbag wiring harness routes through the clock spring under the steering wheel. Long-term use wears the internal flat cable insulation, shorting the ignition wire (typically an odd-numbered pin) to the metal frame or ground wire.
  • 2Physical damage to the airbag wiring harness: Bracket edges, screws, or metal clips may crush the internal dashboard wiring harness during assembly or repair. Damaged insulation contacts body ground, especially at the instrument panel cross member (Cross Car Beam) routing hole.
  • 3Connector water ingress and corrosion: Poor sealing of the front passenger airbag connector (usually located behind the glove box or on the right side of the dashboard). After an A/C condensate leak or vehicle wading, electrolytic corrosion forms between the pins, creating a low-resistance path to ground.
  • 4Internal airbag module fault: The internal bridge wire of the gas generator igniter shorts to the housing, or moisture in the igniter charge causes an abnormal resistance drop. This condition is rare and unrepairable via the external wiring harness.
  • 5SRS ECU internal drive circuit fault: ACU internal ignition drive transistor (Squib Driver IC) breakdown or short to ground causes false detection. Verify by substitution.
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment. Wear an anti-static wrist strap. Do not use a multimeter resistance setting to directly measure the airbag igniter pins (use a dedicated high-impedance diagnostic device).
  • 2
    Initial diagnosis: Connect the VDS to read all DTCs and freeze frame data. Confirm if this is a current fault (Current DTC). Check the SRS warning lamp status on the instrument cluster. Record the vehicle condition at the time of the fault (e.g., driving on rough roads, wading, or recent repair history).
  • 3
    Wiring visual inspection: Remove the front passenger lower dashboard trim panel and glove box. Inspect the entire airbag harness routing (typically wrapped in yellow corrugated conduit) from the ACU to the airbag module. Specifically check contact points between the harness and the dashboard metal frame, and at retaining clips, for wear, indentations, or damaged insulation.
  • 4
    Connector check: Disconnect the front passenger airbag connector (usually includes a shorting bar/pin). Check the pins for oxidation, backed-out terminals, or signs of water ingress. Measure the resistance to ground on the wiring harness side: it must be greater than 10kΩ. If the resistance is close to 0Ω, a short to ground exists.
  • 5
    Clock spring test: Disconnect the clock spring below the steering wheel from the main wiring harness. Measure the resistance to ground at the clock spring input and output terminals. If the input terminal is normal but the output terminal is shorted, replace the clock spring assembly.
  • 6
    Isolation check: Replace the actual airbag module with an airbag simulator (2Ω dummy load). Clear the fault code and power on. If the fault code disappears, the airbag module is faulty. If the fault remains, the wiring harness or ACU is faulty.
  • 7
    Repair and Replacement: Repair the damaged wiring harness (use heat shrink tubing or replace the entire harness section); replace the damaged connector or clock spring. If diagnostics confirm an ACU fault, replace the airbag control module and perform coding configuration.
  • 8
    System verification: Reconnect all components, clear the DTC, and perform an ignition cycle test. Use VDS to perform the SRS system Functional Test. Confirm the resistance value is within the normal range (typically 2.0-3.0Ω) and verify no new fault codes appear.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal short in clock spring caused intermittent fault

✓
Vehicle: Qin Pro DM 2019. Customer reported intermittent airbag warning light on the dashboard, especially when turning the steering wheel. Scanned with VDS and found history fault B161111. Removed and inspected the clock spring beneath the steering wheel; found the internal flat cable second layer had worn through and shorted to the grounding spring plate due to prolonged twisting. Replaced the clock spring assembly (part number: BYD-3637A0-XXXX), which resolved the fault and restored resistance to 2.4Ω.
BYD DTC AI AnalysisFrom Chinese market (translated)

Dashboard wiring harness chafing caused a hard short.

✓
Model: E2 2020. After accident repairs, the airbag light stayed on. Inspection found that when the repair shop reinstalled the dashboard, they trapped the passenger airbag harness (yellow) under the dashboard crossbeam mounting bracket. The insulation wore through, letting the copper core contact the chassis directly. Repaired the damaged harness (re-wrapped and rerouted), fitted a rubber protective sleeve, and resolved the fault.
BYD DTC AI AnalysisFrom Chinese market (translated)

Air conditioning water leak caused connector corrosion

✓
Model: Qin EV 2019. DTC B161111 appeared after the vehicle drove through water. Removed the glovebox and found mud and water traces inside the front passenger airbag connector (2-pin) behind it. Copper corrosion between the pins dropped resistance to ground to 0.8 Ω. Cleaned the connector contacts, replaced the seal, and cleared the air conditioning drain tube blockage. Cleared the fault code; it has not returned.
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal short circuit in airbag module igniter

✓
Model: E3 2020. After ruling out wiring harness and clock spring faults, the system tested normally with a dummy load, but the fault returned when the original airbag was connected. Disassembled the airbag module: resistance between igniter pin and housing measured 0.5Ω (normal: infinite), indicating an internal short in the gas generator. Replaced the passenger airbag assembly and the system returned to normal.
BYD DTC AI AnalysisFrom Chinese market (translated)

SRS ECU driver chip failure

✓
Vehicle: 2018 Qin Pro (petrol). No accident history. Multiple airbag DTCs suddenly appeared (including B161111). Measured the passenger airbag wiring harness resistance to ground: normal. However, the ACU still reported a short circuit. Replaced the airbag control module (ACU), performed VIN coding and crash sensor calibration. All DTCs cleared; system self-test passed.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
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. Sources: [1]