AU
B162111

DTC B162111 is a BYD SRS (Supplemental Restraint System) diagnostic code indicating a short to ground in the driver-side side airbag ignition circuit — Atto 8

Safety System

DTC B162111 is a BYD SRS (Supplemental Restraint System) diagnostic code indicating a short to ground in the driver-side side airbag ignition circuit.

In BYD electrical architecture, this fault indicates the airbag control unit (ACU) detects abnormally low igniter circuit resistance (close to 0Ω) in the driver seat side airbag (typically integrated into the seat backrest or B-pillar), falling below the calibrated threshold (typically < 1.0Ω).

This signifies an unintended connection between the positive or negative wire in the ignition circuit and the vehicle chassis (GND).

This fault causes the ACU to flag the airbag as unsafe, immediately illuminate the instrument cluster SRS warning lamp, and disable deployment of the affected side airbag.

In a collision, this airbag fails to inflate, severely compromising occupant side-impact protection.

Additionally, the short circuit can trigger overcurrent protection in the internal ACU driver chip and, in extreme cases, risk unintended deployment, forcing the system into fail-safe mode.

5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Mechanical wear of the under-seat wiring harness: Frequent fore-and-aft or height adjustments of the driver's seat repeatedly bend the yellow SRS wiring harness (especially between the GJK mating connector and the seat frame). The insulation wears through, causing a short to ground against the metal seat frame or vehicle body.
  • 2Connector water ingress and corrosion: During interior cleaning or driving through water, liquid seeps into the dedicated SRS connector (GJK mating point) under the driver's seat, causing electrolyte conduction between terminals or a short to ground due to verdigris.
  • 3Airbag module internal igniter short circuit: Manufacturing defects or prolonged exposure to high temperatures and humidity cause the insulation layer to fail, shorting the gas generator bridgewire directly to the metal housing.
  • 4B-pillar wiring harness retention failure: The wiring harness clip inside the left B-pillar trim panel detaches, causing the harness to vibrate while the vehicle is in motion and rub against the sharp edge of the body sheet metal, resulting in insulation damage and a short to ground.
  • 5Improper collision repair: During collision repairs, incorrectly securing the SRS wiring harness allows seat rail bolts to crush the harness or over-tightened cable ties to cut the insulation, causing an intermittent or permanent short to ground.
What To Do
  • 1
    Safety Preparation and System Power-Down: Turn the vehicle OFF, disconnect the 12V low-voltage 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 directly measure the airbag circuit with a standard multimeter (use a dedicated diagnostic resistance meter with a current-limiting function).
  • 2
    Fault Code Confirmation and Freeze Frame Analysis: Use a BYD VDS2000 or ED400 diagnostic tool to access the SRS system. Read and confirm B162111 is a current fault (Active). Record freeze frame data (such as vehicle mileage and ambient temperature) to determine if the fault is intermittent.
  • 3
    Visual and physical inspection: Remove the driver's seat (leave the wiring harness connected). Inspect the GJK mating connector on the yellow SRS wiring harness under the seat for backed-out terminals, signs of water ingress, corrosion, or bent pins. Inspect the wiring harness corrugated conduit for wear or burn marks. Verify the wiring harness retaining clips inside the B-pillar trim panel are intact.
  • 4
    Electrical isolation diagnosis: Disconnect the driver side airbag module connector (usually located under the seat or at the B-pillar). Use a high-impedance multimeter (≥10 MΩ) to measure the resistance between the harness-side (vehicle-side) connector and body ground. Normal resistance is >1 MΩ (open circuit). If the resistance is <10 Ω, this confirms a harness short to ground. If the harness side is normal, measure the resistance between the airbag module pins. Normal resistance is 2.0-3.0 Ω. A reading near 0 Ω indicates an internal module short circuit.
  • 5
    Wiring harness repair or replacement: For a wiring harness short circuit, locate the damaged point and cut out the damaged section. Solder a high-temperature cable of the same specification (typically 0.5 mm² or larger, matching colour) to repair the harness. Insulate the repair with double-layer heat-shrink tubing (waterproof inner layer, wear-resistant outer layer). Reroute the wiring harness to add movement slack, and secure it using fabric tape and dedicated clips. Maintain a clearance of at least 20 mm from the seat slide rail and frame.
  • 6
    Component replacement: If diagnosis confirms an internal short circuit in the airbag module, replace the driver-side side airbag module assembly (part number must match vehicle model year). Install a new single-use connector position assurance (CPA) lock during replacement for a reliable connection. Never use a multimeter to directly measure the new airbag module resistance (this may trigger the igniter).
  • 7
    System reset and calibration: Reconnect all connectors and the battery negative terminal. Turn the ignition switch to ON. Use the diagnostic tool to clear the fault code. Perform 'SRS system self-diagnosis' and 'crash sensor calibration' (required on some models). Confirm the B162111 status changes to 'history code' and clears successfully, and the instrument cluster SRS warning lamp turns off after the self-check. Perform a final road test to verify the repair.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Yuan Plus / ATTO 3 driver side airbag wiring harness interference fault

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Symptoms: The SRS warning light illuminated on the dashboard while driving. The scan tool retrieved active fault code B162111. Diagnosis: Removal of the driver's seat revealed that the insulation at pins 14/15 of the GJK harness connector beneath the seat had worn through against the metal bracket of the seat height adjustment mechanism, allowing the copper conductor to short directly to earth. Harness-side resistance to earth measured 0.8 Ω, confirming the short circuit. Repair: Cut out the 50 mm damaged section of harness, re-crimped the terminals, and rerouted the wiring. Installed rubber protective sheathing and cable ties at the interference point to secure the harness and maintain safe clearance from the adjustment mechanism. Cleared the fault code; the SRS system returned to normal operation.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Water ingress shorted the under-seat connector on a BYD Qin Pro DM.

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Symptom: After wading through water, the SRS light stayed on with DTC B162111. Diagnosis: Inspected the yellow SRS connector under the driver's seat and found water stains and green copper corrosion inside, causing the terminals to short to the connector housing (earth). The water seeped in through the carpet during wading, and the connector seal ring had aged and failed. Repair: Thoroughly cleaned the connector terminals with electrical contact cleaner and anhydrous ethanol, then blow-dried them. Replaced the waterproof seal ring and connector housing. Dried the interior carpet and repaired the chassis sealing defect. Fault cleared.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD E2 side airbag module internal igniter short circuit

✓
Symptoms: During new vehicle delivery PDI, the SRS light would not extinguish. Retrieved DTC B162111. Diagnostic process: Disconnected the airbag module connector under the seat. Measured vehicle-side harness resistance to ground: infinite (normal). Measured resistance between the two pins on the airbag module (seat side): 0.3 Ω (well below the standard 2–3 Ω). Determined an internal bridge wire short circuit in the gas generator. Solution: Replaced the driver-side side airbag module assembly together with the seat trim cover, as the module is integrated into the seat. After replacement, performed ACU configuration and system calibration. Cleared the DTC, and the SRS light extinguished.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Pro intermittent short-to-ground fault

✓
Symptoms: The SRS warning light illuminated intermittently, occurring more frequently on rough roads. The scan tool showed B162111 as an intermittent fault. Diagnosis: Static resistance measurements of the wiring harness were normal, but resistance readings jumped when the harness was shaken. Further inspection revealed the airbag wiring harness retaining clip inside the left B-pillar trim had detached, allowing the harness to rub against the metal body bracket while driving. The insulation had partially worn through but was not completely split. Repair: Repaired the damaged wiring (insulated with heat shrink tubing), reinstalled the B-pillar harness retaining clip, and applied felt tape to prevent chafing where the harness contacts the body. Road tested for 20 km; no fault recurrence.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin EV wiring harness improperly secured after accident repair

✓
Symptoms: SRS warning light stays on after left front side collision repair. DTC B162111. Diagnosis: The previous repair did not properly secure the new SRS wiring harness under the seat. A seat rail mounting screw pinched the harness, damaging the insulation and causing a short to ground. Solution: Replaced the damaged harness section (seat-to-floor section). Secured the harness per the workshop manual, using the specified clips and cable ties, and maintaining a minimum 20mm clearance from the seat rails to prevent interference through the full seat travel.
Original source ↗
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]