AU
B161111

DTC B161111 indicates a short to ground in the front passenger airbag (PAB) ignition circuit — Atto 8

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 8
  • 1Short circuit between internal conductor layers of the clock spring (spiral cable): The front passenger airbag wiring harness routes through the clock spring under the steering wheel. Prolonged use wears the internal flat cable insulation, shorting the ignition wire (typically an odd-numbered pin) to the metal frame or ground wire.
  • 2Airbag wiring harness physical damage: Bracket edges, screws, or metal clips crush the internal dashboard wiring harness during assembly or repair. The damaged insulation contacts body ground, especially at the Cross Car Beam routing hole.
  • 3Connector water ingress and corrosion: The front passenger airbag connector (usually located behind the glove box or on the right side of the dashboard) is poorly sealed. Following an A/C condensate leak or vehicle wading, electrolytic corrosion forms between the pins and creates a low-resistance path to ground.
  • 4Airbag module internal fault: the bridge wire inside the gas generator igniter shorts to the housing, or moisture in the igniter charge causes an abnormal resistance drop. This condition is relatively 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. Wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment. Wear an anti-static wrist strap. Do not measure airbag igniter pins directly with a multimeter resistance setting (use a dedicated high-impedance diagnostic device).
  • 2
    Initial diagnosis: Connect the VDS to read all DTCs and freeze frame data. Confirm if it is a current fault (Current DTC). Check the instrument cluster SRS warning lamp status. Record the vehicle condition when the fault occurred (e.g., driving over rough roads, driving through water, or recent repair history).
  • 3
    Visual wiring inspection: Remove the front passenger dashboard lower trim panel and glove box. Inspect the entire airbag wiring harness route (usually wrapped in yellow corrugated conduit) from the ACU to the airbag module. Check contact points between the harness and the dashboard metal frame, and retaining clip locations, for abrasion, indentations, or damaged insulation.
  • 4
    Connector check: Disconnect the front passenger airbag connector (usually incorporating a shorting clip/bar). Check the pins for oxidation, backed-out terminals, or water ingress. Measure the resistance to ground on the wiring harness side: it must exceed 10 kΩ. A resistance near 0 Ω indicates a short to ground.
  • 5
    Clock spring test: Disconnect the clock spring under 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) and replace the damaged connector or clock spring. If testing confirms an ACU fault, replace the airbag control module and perform coding.
  • 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 (usually 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 8 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. Sources: [1]