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 — Seal U

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 — Seal U
  • 1Long-term bending and wear of the yellow SRS wiring harness under the seat damages the insulation, causing a short to ground or 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). Although the probability is low, do not rule it out.
  • 4Liquid penetrated the seat during vehicle wading or interior cleaning, causing a short circuit in the airbag connector or wiring harness.
  • 5Fault in the SRS control unit internal detection circuit causing a false alarm, or wiring harness crushed or 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 to fully discharge the SRS capacitor and 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 check: 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 infinity (OL). If continuity exists, repair the damaged harness section or replace the harness.
  • 6
    ECU-side check: Inspect SRS ECU connector B (or 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 (use double-layer heat-shrink tubing for insulation), 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. Confirm 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 Seal U 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]