AU
B167300

This fault code indicates a communication failure between the airbag control module (SRS ECU) and the right side impact sensor (SIS) — Seal U

Safety System

This fault code indicates a communication failure between the airbag control module (SRS ECU) and the right side impact sensor (SIS).

On models such as the BYD Qin PRO, the right side impact sensor typically mounts inside the right front door trim panel, below the right B-pillar, or beside the right front seat.

The sensor connects to the SRS ECU via a LIN bus or hardwire to monitor real-time lateral acceleration changes on the right side of the vehicle.

The ECU triggers DTC B167300 if it fails to receive valid data frames from the sensor over several consecutive ignition cycles, detects a bus short or open circuit, or encounters a data checksum failure.

This fault may prevent the right side airbags (curtain and seat side airbags) from deploying during a side impact.

Consequently, the airbag warning lamp (SRS lamp) illuminates continuously, and the vehicle passive safety system enters degraded protection mode.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1Internal circuit damage in the right side impact sensor (e.g., MEMS accelerometer chip failure or internal capacitor breakdown), common after vehicle water ingress or a previous side impact.
  • 2Loose, backed-out, oxidized, or water-damaged harness connectors between the sensor and the SRS ECU, particularly harness wear at the door hinge and inside the sill trim caused by frequent door operation or wading.
  • 3Poor contact in the sensor power supply circuit (+B power) or ground circuit (GND) causing abnormal voltage (normal: 9-16V; voltage below 8V may trigger a communication fault).
  • 4SRS ECU internal communication interface driver chip fault or outdated software version (early Qin PRO models require an SRS software upgrade), preventing correct parsing of sensor data.
  • 5Accidental damage to the sensor wiring harness during vehicle modification or repair work (such as window tinting, routing dash cam wiring, or replacing the inner door trim panel) causes a hidden open or short circuit.
What To Do
  • 1
    Use BYD dedicated diagnostic tool VDS2000 or Launch X-431 to access the SRS system. Read the complete DTC freeze frame data (record vehicle speed, temperature, and voltage at the time of the fault). Clear the fault code to distinguish between an intermittent and a persistent fault.
  • 2
    Visually inspect the right front door trim panel, lower B-pillar trim panel, and sill wiring harness sleeve. Specifically check the wiring harness at the door hinge for breaks, wear, or signs of water ingress. Check the right front carpet and the area under the seat for water marks (to determine if the vehicle has water damage).
  • 3
    Disconnect the battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor. Remove the right side impact sensor (located in the door or B-pillar; refer to the vehicle repair manual for details). Inspect the connector terminals for backed-out pins, oxidation, or water ingress whitening. Measure the voltage between pin 1 (power supply) and pin 2 (ground); this should be battery voltage. Measure the voltage at pin 3 (LIN line) to ground; this should be 8-11V.
  • 4
    Disconnect the SRS ECU connector (located under the center console or center tunnel). Use a multimeter to measure the continuity of the LIN line, power line, and ground line between the ECU and the sensor (must be less than 1Ω). Measure the insulation to ground and to power (must be greater than 10MΩ) to rule out open or short circuits in the wiring harness.
  • 5
    If the wiring harness tests normal, use an oscilloscope to measure the LIN bus waveform (normally a square-wave signal with a dominant level of 0V and a recessive level of 12V, and a typical baud rate of 19.2kbps). If the waveform is abnormal, replace the sensor. If the waveform is normal but the ECU still reports the fault, replace the SRS ECU.
  • 6
    After installing a new sensor or repairing the wiring harness, reconnect all connectors and connect the battery. Use the diagnostic tool to perform 'SRS System Configuration' or 'Sensor Calibration' (required on some models). Clear the fault code and perform a system self-check to confirm B167300 does not return.
  • 7
    Verify the right side crash sensor function: Use the diagnostic tool to read the data stream. Tap the vehicle body near the sensor mounting position by hand with moderate force. Observe if the 'Right Side Acceleration' value changes with the tapping (the value should fluctuate noticeably) to confirm the system has returned to normal.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin Pro DM: Water ingress into right front sill after wading caused sensor corrosion

✓
A 2019 Qin Pro DM presented with the airbag warning light constantly illuminated. VDS retrieved DTCs B167300 (right side impact sensor communication error) and U0151 (lost communication with SRS). Inspection revealed the vehicle had water ingress, with water pooling inside the right front sill trim. Removing the right front seat and B-pillar lower trim exposed severely oxidised, white connector pins on the side impact sensor. Removed the water, cleaned the connector with electronic cleaner, applied conductive grease, and replaced the right side impact sensor (part number: BYD-3636400). The sensor had water ingress, likely damaging its internal circuit. After replacement, the fault cleared, the SRS light went out, and the data stream returned to normal.
BYD DTC AI AnalysisFrom Chinese market (translated)

Worn right front door wiring harness causes intermittent communication fault on Qin PRO petrol version

✓
2018 BYD Qin Pro petrol. Airbag warning light intermittently illuminated, particularly when driving over speed bumps. Scan tool showed B167300 as a historical fault. Inspected wiring harness at right front door hinge area and found harness sheath cracked from repeated door opening and closing. Internal LIN signal wire copper strands had fractured with only a few strands remaining connected, causing intermittent open circuit. Repair: cut out damaged harness section, re-soldered wires, and applied waterproof insulation. Adjusted harness routing to avoid chafing against door metal edge and fitted protective corrugated conduit. Road tested 50 km after repair; fault did not return.
BYD DTC AI AnalysisFrom Chinese market (translated)

Door speaker modification caused the sensor connector to come loose.

✓
A 2019 Qin Pro DM developed an illuminated airbag warning light after the owner modified the right front door speaker. The fault code B167300 was read. Inspection found that the person who did the modification had not properly reconnected the side impact sensor connector (mounted inside the door trim panel) during removal and refitting of the right front door trim panel. The plug was not fully locked, causing intermittent contact from vehicle vibration. The technician firmly reconnected the sensor connector, ensured the lock tab fully engaged, secured the wiring harness with cable ties to prevent movement, and cleared the fault code. The system returned to normal afterward.
BYD DTC AI AnalysisFrom Chinese market (translated)

After accident repair, unconfigured sensors cause communication error in Qin Pro EV.

✓
2020 BYD Qin Pro EV. After a right-side side impact collision, a workshop replaced the right front door and side impact sensor. The airbag warning light stayed on, logging DTC B167300. Inspection found the replacement sensor was an aftermarket part and the new sensor configuration had not been performed using BYD VDS. Qin Pro vehicles require online configuration after SRS component replacement; otherwise the ECU cannot recognise the new sensor ID code. Solution: Used a genuine VDS2000 diagnostic tool to access ‘SRS System – Special Functions – Configuration/Coding’, ran the right side impact sensor configuration, then cleared the DTCs. SRS self-test passed.
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]