AU
B162C-00

DTC B162C-00 indicates the SRS (Supplemental Restraint System) control unit detects resistance exceeding the calibrated threshold in the driver side airbag ignition circuit — Atto 3

Safety System

DTC B162C-00 indicates the SRS (Supplemental Restraint System) control unit detects resistance exceeding the calibrated threshold in the driver side airbag ignition circuit.

The driver side airbag typically mounts in the side of the driver seat backrest or inside the door trim panel.

Normal circuit resistance ranges from 2-3 ohms; the fault threshold typically exceeds 3.5-4 ohms.

The SRS ECU monitors circuit integrity by sending a low-current signal through its internal detection circuit to the airbag igniter.

High-resistance connections (e.g., poor contact, loose harness connections, oxidation, or partial wire breaks) increase total circuit resistance, causing the ECU to register a high-resistance fault.

This fault severely compromises side-impact protection.

Excessive resistance limits current, potentially causing the driver side airbag to deploy late or fail to deploy during a collision.

The system illuminates the SRS warning lamp and may disable the entire airbag system, resulting in a complete loss of collision protection.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Fatigue fracture or poor connection in the under-seat wiring harness: Frequent forward and backward adjustment of the driver's seat repeatedly bends the airbag wiring harness secured under the seat, partially breaking the internal copper strands while the insulation remains intact, creating a high-resistance connection.
  • 2Poor connector contact: Moisture, oxidation, or an incompletely engaged locking tab increases contact resistance at the seat side airbag connector (usually a yellow plug).
  • 3Improper modification or repair: Airbag connector not fully seated during reinstallation after seat leather trimming, heated pad retrofitting, or accident repair, or the seat slide rail crushed and damaged the wiring harness.
  • 4Airbag module internal fault: Airbag igniter internal resistance wire aging or poor connection (rare, usually accompanied by unstable or infinite resistance).
  • 5Improper wiring harness routing: A detached wiring harness retaining clip causes the harness to stretch or rub against other components during seat movement, resulting in an intermittent open circuit.
What To Do
  • 1
    Safety preparation: Switch off the ignition, disconnect the 12V battery negative terminal, and wait at least 3 minutes (to fully discharge the SRS capacitor and prevent accidental airbag deployment).
  • 2
    Fault confirmation: Connect the BYD dedicated diagnostic tool (VDS or ED400). Read the SRS system fault codes. Confirm B162C-00 is a current fault, not a history fault. Record the freeze frame data.
  • 3
    Visual inspection: Remove the driver's seat side trim panel. Verify the airbag connector (yellow) is fully seated and the locking tab is engaged. Inspect the terminals for oxidation or water ingress corrosion.
  • 4
    Static resistance measurement: Disconnect the airbag connector. Use a digital multimeter to measure the airbag unit resistance (2-3 ohms). If normal, the fault is in the wiring harness. If the resistance is too high, replace the airbag assembly.
  • 5
    Harness continuity check: Measure the harness resistance between the SRS ECU and the airbag connector. Resistance must be less than 1 ohm. Focus on the harness under the seat. Peel back the corrugated conduit to check for hidden breaks.
  • 6
    Dynamic test: With the diagnostic tool connected, move the seat forward and backward and observe if the data stream resistance value fluctuates. If the resistance changes with seat position, confirm an intermittent open circuit in the wiring harness.
  • 7
    Repair and replacement: Repair the broken wiring harness (solder and insulate with heat-shrink tubing) or replace the wiring harness assembly. Reroute the harness with sufficient slack to prevent the seat slide rail from pinching it.
  • 8
    System reset: Connect all connectors, reinstall the seat, and connect the battery. Use the diagnostic tool to clear the fault code and perform the SRS system self-check (requires vehicle speed at 0, normal system voltage, etc.). Confirm the warning light turns off and the fault code does not return.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Long-term flexing caused an intermittent connection in the BYD Qin seat wiring harness.

✓
The SRS warning light stayed on with DTC B162C-00 stored. Found the wiring harness under the driver's seat had internal wire breaks but undamaged outer insulation, caused by repeated forward and backward seat adjustment. Resistance fluctuated between 5 and 8 ohms. Replaced the seat wiring harness assembly and repositioned the harness mounting points to increase slack, preventing excessive stretching during seat movement. After clearing the DTC, the system returned to normal.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Pro seat slide rail crushed wiring harness

✓
Owner reported the SRS warning lamp illuminating intermittently; scan revealed DTC B162C-00. Diagnosis found the seat rail mounting bolts overtightened, crushing the wiring harness beneath and causing partial fracture of the internal copper conductors. The airbag module tested normal, but circuit resistance fluctuated between 3 and 8 ohms. Fix: Rerouted the wiring to avoid the seat rail pinch point, replaced the damaged harness section, adjusted bolt torque, and fitted a protective sleeve to the harness. Fault rectified.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Tang DM connector not properly secured after collision repair

✓
After collision repair, the SRS warning light remained on with DTC B162C-00. Inspection found that the driver's seat had been removed and reinstalled. The side airbag connector plug was not fully inserted (locking clip not secured), causing high contact resistance (measured 4.5 ohms). Reorganized the seat wiring harness to eliminate any pinching or interference, reconnected the airbag connector and confirmed the locking click, then performed the SRS calibration, resolving the fault.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Seat modification caused poor contact on BYD e5

✓
The vehicle had no accident history, but B162C-00 set immediately after leather seat reupholstery. Inspection found the side airbag had been removed during the modification. The connector wasn't fully seated upon reinstallation, and the terminals showed slight oxidation. Repair: - Cleaned the connector terminals and applied conductive grease. - Correctly reinstalled the airbag module and restored factory wiring connections. - Cleared the fault code; self-test passed.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Intermittent loose connection in BYD Qin Pro wiring

✓
The SRS warning light came on intermittently and turned off automatically. We diagnosed the fault and found the under-seat wiring harness measured 2.5 ohms when stationary, but resistance increased above 6 ohms when sliding the seat fore and aft. We stripped back the harness sleeve and found a loose internal connection. We cut out the damaged wire section, resoldered it, insulated with heat-shrink tubing, and adjusted the harness mounting bracket to provide more slack. Multiple seat adjustment tests confirmed the fault was resolved.
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]