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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 3

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 3
  • 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 and shorts to the metal seat frame or vehicle ground.
  • 2Connector water ingress and corrosion: During vehicle wading or interior cleaning, liquid enters the dedicated SRS connector (GJK mating point) under the driver's seat, causing electrolyte conduction between terminals or verdigris buildup that results in a short to ground.
  • 3Airbag module internal igniter short circuit: Gas generator bridgewire insulation fails due to manufacturing defects or prolonged exposure to high temperatures and humidity, shorting directly to the metal housing.
  • 4B-pillar wiring harness retention failure: The wiring harness clip inside the left B-pillar trim panel detaches. This allows the harness to shake during vehicle operation and rub against a sharp edge of the body sheet metal, damaging the insulation and causing a short to ground.
  • 5Improper collision repair: Improperly securing the SRS wiring harness during collision repairs allows seat slide rail bolts to pinch the harness, or overly tight cable ties to cut the insulation, causing an intermittent or permanent short to ground.
What To Do
  • 1
    Safety preparation and system power-down: Set the vehicle to 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 use a standard multimeter to measure the airbag circuit directly (use a dedicated diagnostic resistance meter with a current limiting function).
  • 2
    DTC 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 (≥10MΩ) to measure the resistance between the harness-side (vehicle-side) connector and body ground. Normal resistance is >1MΩ (open circuit). A resistance of <10Ω confirms a wiring harness short to ground. If the harness side is normal, measure the resistance between the airbag module-side pins. Normal resistance is 2.0-3.0Ω. A resistance near 0Ω indicates an internal module short circuit.
  • 5
    Wiring harness repair or replacement: For a short circuit in the wiring harness, 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). Redesign the harness routing to provide slack. Secure the harness using fabric tape and dedicated clips. Maintain a clearance of at least 20 mm from the seat slide rails 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 the vehicle model year). Use a new single-use connector position assurance (CPA) lock during replacement to ensure a reliable connection. Never directly measure the new airbag module resistance with a multimeter (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. Execute '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 for verification.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

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

✓
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 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]