AU
B167A00

This DTC indicates the airbag control unit (SRS ECU) detects a communication loss or open circuit at the Right Rear Side Impact Sensor — Seal U

Safety System

This DTC indicates the airbag control unit (SRS ECU) detects a communication loss or open circuit at the Right Rear Side Impact Sensor.

The sensor typically mounts in the right C-pillar, rear sill, or right rear door frame area to monitor acceleration changes during a right rear side impact.

The ECU sets DTC B167A00 when it fails to receive the sensor signal or detects abnormal circuit resistance (open circuit).

This fault disables the right rear side collision detection function.

During a side impact, the system may fail to accurately determine collision severity, causing the side airbag and curtain airbag to fail to deploy or deploy at the incorrect time, severely compromising occupant safety.

3
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Loose sensor wiring harness connector or poor contact: The right rear side impact sensor is located in the body sill or C-pillar area. Driving through water, rough roads, or previous repairs can loosen the connector, back out terminals, or cause oxidation and corrosion.
  • 2Wiring harness open circuit or wear: The sensor wiring harness routes through the door hinge, sill trim panel, or under the carpet. Long-term bending, compression, or underbody scraping may cause internal wire breakage or insulation damage.
  • 3Internal sensor fault: Damage to the internal accelerometer or communication chip prevents the sensor from sending a valid signal to the SRS ECU or results in a high-impedance state.
  • 4SRS ECU internal circuit fault: The internal ECU detection circuit for the corresponding sensor is damaged, triggering a false sensor disconnected fault.
  • 5Improper repair after a vehicle accident: After a right rear collision or repair, the sensor mounting position is not restored, the connector is disconnected, or the wiring harness is pinched and cut.
What To Do
  • 1
    Use the BYD dedicated diagnostic tool (VDS) to read the fault code, confirm whether B167A00 is a current or history fault, view the freeze frame data, and record the vehicle status when the fault occurred.
  • 2
    Disconnect the battery negative terminal and wait at least 3 minutes to fully discharge the SRS system. Remove the right rear sill trim, C-pillar interior trim, or right rear seat (depending on the specific model), then locate the right rear side impact sensor (usually marked SR or SRS, with a yellow connector).
  • 3
    Visually check that the sensor connector is fully inserted. Inspect the connector pins for oxidation, corrosion, backed-out pins, or deformation. If necessary, clean the pins with electrical contact cleaner and apply conductive grease.
  • 4
    Use a multimeter to measure wiring harness continuity between the sensor connector and the SRS ECU: check the continuity of the power wire (usually 12V), ground wire, and signal wire (LIN wire or hardwire). Standard resistance must be less than 1 Ω. Check each wire for short circuits to ground or power. Insulation resistance must be greater than 10 MΩ.
  • 5
    If the wiring harness is normal, use an oscilloscope to check the LIN bus communication waveform (if applicable) or measure the sensor operating voltage. If the sensor power supply and ground are normal but there is no signal output, replace the right rear side impact sensor (Note: Sensors may differ between vehicle models; verify the part number).
  • 6
    After repairing the wiring harness or replacing the sensor, reconnect all connectors, install the interior trim panels, and connect the battery. Use the diagnostic tool to clear the fault code and perform an SRS system self-check. Confirm B167A00 no longer appears. Finally, perform a road test or simulation test to verify normal system communication.
Real-World Cases
BYD DTC AI Analysis

Intermittent warning caused by corrosion of right rear sill connector after water ingress

✓
2019 BYD Qin EV. Owner reported an intermittent airbag warning light on the dashboard. Scanned with VDS and found current DTC B167A00. Inspected the right rear side impact sensor and found green oxide on the wiring harness connector beneath the sill trim panel. The vehicle had been driven through water, causing water ingress and corrosion to the connector. Cleaned the connector pins, applied conductive grease, and wrapped with waterproof tape. Cleared the DTC and it did not return; the airbag warning light went out.
BYD DTC AI Analysis

C-pillar sensor connector not fully seated after accident repair

✓
A 2018 Qin PRO DM had a scraping accident on the right rear side. After repairs at an independent workshop, the airbag warning light came on. The diagnostic scanner showed code B167A00. Removed the right C-pillar trim panel and found the side impact sensor connector was not fully seated (locking tab not engaged), likely pulled loose during trim installation after the accident. Reseated the connector firmly and confirmed the locking tab was properly engaged, then cleared the fault codes. The system returned to normal.
BYD DTC AI Analysis

Wiring harness chafed through at sill trim clip, open circuit

✓
A 2020 BYD E3 came in with the airbag warning light staying on after driving over a rough road. Diagnosis pulled current fault code B167A00. Removing the right rear sill trim panel revealed the trim retaining clip had been compressing the sensor wiring harness over time, causing the internal copper wire to break while the insulation remained intact (hidden open circuit). Stripping back the harness exposed the broken wire. The technician soldered the connection and applied waterproof insulation, then rerouted the harness to avoid interference with the clip, clearing the fault.
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.