AU
B163A-00

DTC B163A-00 indicates the SRS (Supplemental Restraint System) ECU detects 0Ω resistance in the right front seat side airbag circuit, technically defined as a short circuit — Atto 3

Safety System

DTC B163A-00 indicates the SRS (Supplemental Restraint System) ECU detects 0Ω resistance in the right front seat side airbag circuit, technically defined as a short circuit.

Normal airbag inflator resistance ranges from 1.5-3.5Ω (typically 2.0±0.5Ω).

A 0Ω reading indicates a short to ground, a short to power, or an internal short within the airbag assembly.

This fault prevents the side airbag from deploying during a collision or, in extreme cases, causes accidental deployment due to wiring interference.

The seat houses the side airbag and undergoes frequent fore-aft and angle adjustments.

This movement subjects the wiring harness between the seat and floor to long-term bending, making it a common failure point.

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Long-term bending and wear damage the insulation on the yellow SRS wiring harness under the seat, causing a short to ground or short to power. This is the most common cause.
  • 2Bent, backed out, or corroded internal pins, or water ingress in the right front seat side airbag connector (usually located under or on the side of the seat), causing a short circuit.
  • 3Internal short circuit failure of the side airbag unit (gas generator) (low probability, but possible).
  • 4Liquid penetrated the seat during vehicle wading or interior cleaning, causing a short circuit in the airbag connector or wiring harness.
  • 5SRS control unit internal detection circuit fault causing a false warning, or wiring harness pinched and damaged during seat removal, installation, or modification.
What To Do
  • 1
    Safety preparation: Turn off the vehicle, disconnect the 12V battery negative terminal, and wait at least 90 seconds for the SRS capacitor to discharge completely to prevent accidental airbag deployment.
  • 2
    Visual inspection: Remove the right front seat (if necessary). Carefully inspect the dedicated yellow SRS wiring harness under the seat and at the seat rails for wear, damaged insulation, or crush marks. Focus on friction points between the wiring harness and the seat frame.
  • 3
    Connector inspection: Disconnect the right front seat side airbag connector (yellow locking tab). Check inside the connector for water ingress, corrosion, bent pins or foreign matter. Clean and blow dry the connector.
  • 4
    Airbag unit measurement: Use a digital multimeter to measure the resistance between the two terminals of the side airbag unit (gas generator). Normal resistance is 1.5-3.5 Ω. If the resistance is close to 0 Ω, replace the airbag assembly.
  • 5
    Harness insulation check: Measure the resistance from both airbag harness terminals to ground and to the power supply (+12V). Normal resistance is infinite (OL). If continuity exists, repair the damaged section or replace the harness.
  • 6
    ECU-side check: Check SRS ECU connector B (or the corresponding seat airbag pin) for looseness or corrosion. If necessary, measure wiring continuity from the ECU to the airbag.
  • 7
    Repair or replace: Based on inspection results, repair the wiring harness (insulate with double-layer heat-shrink tubing), or replace the airbag assembly or SRS ECU.
  • 8
    System reset: Reconnect all connectors, reinstall the seat, and connect the battery. Use the dedicated diagnostic tool to clear the fault code and perform an SRS system self-check. Verify B163A-00 does not return and the airbag warning light is off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin EV450 right front seat wiring harness worn through, causing a short circuit

✓
After accident repairs, the vehicle reported DTC B163A-00. Inspection found the right front seat deformed in the collision. Seat frame burrs cut through the SRS wiring harness insulation, causing a short to ground. Repaired the damaged harness section, wrapped the wiring in abrasion-resistant corrugated tubing, and adjusted the position of the seat frame burrs. Fault cleared.
BYD DTC AI AnalysisFrom Chinese market (translated)

Water ingress corrosion at connector under E1 seat

✓
After driving through water, the airbag warning light came on. Scanned DTC B163A-00. Removed and inspected the airbag connector under the right front seat and found clear water stains and green corrosion inside. Cause: Connector seal ageing allowed water ingress when wading. Solution: Thoroughly cleaned the connector and replaced it with a new waterproof connector. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin 100 side airbag internal short circuit

✓
During normal operation, the airbag warning light illuminated intermittently. DTC B163A-00 appeared sporadically. Inspected the wiring harness: found no damage, connectors normal. Disconnected the airbag connector and measured resistance directly at the airbag unit. Found occasional 0.2 Ω readings (unstable). Replaced the right front seat side airbag assembly, which completely resolved the fault.
BYD DTC AI AnalysisFrom Chinese market (translated)

Modified seat pinched the wiring harness, causing a short circuit.

✓
B163A-00 appeared one week after the owner installed racing seats. Inspection found the modified seat bracket interfered with the factory SRS wiring harness, pinching the harness between the seat rail and floor, causing a short circuit. Fix: Rewired the harness, rerouted it away from moving parts, and either reinstalled the standard seats or ensured the modified parts did not interfere with the harness.
BYD DTC AI AnalysisFrom Chinese market (translated)

SRS ECU software false positive (resistance detection threshold drift)

✓
Multiple checks confirmed normal resistance (2.1 Ω) for the wiring harness and airbag assembly, but the ECU continued to report code B163A-00. An oscilloscope detected intermittent short-circuit pulses in the wiring harness. The root cause was abnormal sensitivity in the ECU's internal detection circuit. Updating the SRS ECU software to the latest version resolved the fault; it has not recurred.
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]