AU
B162B1A

This DTC indicates the driver side airbag squib resistance falls below the SRS control unit threshold (typically <1 — Atto 8

Safety System

This DTC indicates the driver side airbag squib resistance falls below the SRS control unit threshold (typically <1.6Ω).

Normal airbag squib resistance ranges from 1.6Ω to 2.4Ω.

Low resistance indicates an abnormal short-circuit path in the circuit.

Potential causes include an internal airbag squib short circuit, a wiring harness short to ground, or a grounded connector terminal.

The SRS system classifies this fault as an unintended deployment risk, automatically disconnects the airbag circuit, and illuminates the airbag warning lamp.

During a side impact, the airbag may fail to deploy, disabling driver side protection.

Additionally, the BYD SRS fail-safe mechanism may trigger the seat belt pretensioner linked protection logic, compromising overall passive safety system performance.

4
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Driver side airbag igniter internal short circuit (airbag assembly fault, possibly due to manufacturing defect or prolonged moisture exposure)
  • 2Worn wiring harness insulation under the seat or inside the B-pillar causing a short to ground (commonly due to frequent seat adjustment or foreign objects pinching and damaging the harness).
  • 3Airbag connector (yellow plug) short circuit due to water ingress, oxidation, or terminal deformation (common after vehicle wading or washing).
  • 4Internal short circuit in the clock spring or seat wiring harness reel (e.g., long-term bending fatigue where the side airbag wiring harness passes through moving parts)
  • 5SRS control unit internal monitoring circuit fault (abnormal control board sampling resistor or software false alarm)
What To Do
  • 1
    Use the BYD dedicated diagnostic tool (VDS2000/VDS2100) to read all DTCs and freeze frame data. Record the environmental conditions at the time of the fault and confirm B162B1A is a current fault, not a history fault.
  • 2
    Disconnect the 12V battery negative terminal and wait at least 3 minutes (some models require 90 seconds; wait 3 minutes to fully discharge the SRS energy storage capacitor) to ensure the system enters a safe state.
  • 3
    Remove the driver seat side trim panel or lower B-pillar trim panel. Locate the side airbag connector (yellow marking, usually under the seat frame or in the middle of the B-pillar). Disconnect the connector and use the dedicated shorting pin to short the harness-side terminals to prevent electrostatic induction.
  • 4
    Measure the resistance on the airbag assembly side using a high-precision digital multimeter (0.1 Ω resolution). Normal value: 1.6–2.4 Ω. A measured value <1.6 Ω or close to 0 Ω indicates an internal short circuit in the airbag assembly. Replace the driver-side side airbag module.
  • 5
    Measure the wiring harness insulation resistance to ground (disconnect the SRS ECU connector and measure the resistance between the harness terminal and body ground). Normal resistance is >1MΩ. If the resistance is too low, trace the wiring to locate the damage. Focus the inspection on the wiring harness under the seat rail, near the seat adjustment mechanism, and inside the B-pillar trim.
  • 6
    Check the connector terminals for corrosion, backed-out pins, or water stains. If necessary, clean with electronic contact cleaner or replace the wiring harness connector.
  • 7
    Reconnect all components, restore battery power, and clear the fault code. Turn the ignition switch to the ON position, verify the SRS warning lamp completes its self-test (turns off after 6 seconds), and confirm the fault does not recur.
  • 8
    Verify system configuration (some models require 'airbag configuration writing'), and finally perform a simulated crash signal test or road test to confirm the repair.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Seat adjustment caused wiring harness wear and short circuit on Qin Pro DM

✓
A 2019 Qin Pro DM with 80,000 km had an intermittent airbag warning light on the dash. DTC B162B1A was stored as a current fault. Inspection found the seat frame pinched the driver's seat wiring harness at the full forward and rearward adjustment positions, wearing through the insulation and causing a short to earth. Disassembling the seat revealed 3 cm of chafed harness at the slide rail end, with exposed copper wires contacting the seat frame. Repaired the damaged harness using heat shrink tubing, rerouted and secured the harness, added corrugated tubing protection, and adjusted the harness slack to prevent future pinching. One month of monitoring showed no recurrence.
BYD DTC AI AnalysisFrom Chinese market (translated)

Water-Damaged Vehicle Airbag Connector Corrosion Case

✓
2018 BYD Qin PRO petrol. After water damage repairs, DTC B162B1A appeared. Inspection found green copper corrosion inside the airbag connector (yellow plug) beneath the seat; insulation resistance between terminals had dropped to 0.8Ω. Analysis determined water entered through the sill trim panel during the water ingress event, and the aged connector seal caused water entry. Repair: Replaced the entire airbag wiring harness connector (cut off old plug, soldered new plug, sealed with waterproof heat-shrink tubing). Measured airbag resistance at 2.1Ω and confirmed normal. Cleared fault codes, and the system returned to normal. Advised owner to check the waterproof condition of the entire vehicle wiring harness.
BYD DTC AI AnalysisFrom Chinese market (translated)

Side Airbag Assembly Internal Short Circuit Replacement Case

✓
A 2019 Qin PRO DM was repaired after an accident, and its left door was replaced. DTC B162B1A then appeared. Checked the wiring harness and connectors—no damage or abnormalities. Disconnected the airbag connector and measured component resistance at only 0.9Ω (far below the standard value), indicating an internal short in the airbag squib. Replaced the driver's side airbag module with a new unit (part number: KFR-5820A0-00). After replacement, resistance measured 2.0Ω. Cleared the fault codes and the SRS system self-test passed. Refurbished airbags in the accident vehicle parts market carry a high risk of internal short circuits; use genuine parts.
BYD DTC AI AnalysisFrom Chinese market (translated)

Case of false alarm due to internal short circuit in clock spring

✓
2019 Qin Pro (petrol). Airbag warning light illuminated intermittently when turning while driving. Scanned and found intermittent DTC B162B1A. Inspection revealed the side airbag harness runs through the clock spring (spiral cable) beneath the steering wheel. Disassembled the clock spring and measured resistance; at a specific steering wheel angle the reading jumped to 0.5 Ω, indicating worn internal slip rings causing a short circuit. Replaced the clock spring assembly (part no. BYD-3740A0-00) and recalibrated the steering angle sensor to resolve the fault. This type of fault commonly results from prolonged dry steering (turning the wheel while stationary), causing excessive wear to the internal slip rings.
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]