AU
B167A

DTC B167A indicates the SRS (Supplemental Restraint System) ECU detects a communication interruption or physical disconnection of the Right Rear Side Impact Sensor (SIS) — Atto 8

Safety System

DTC B167A indicates the SRS (Supplemental Restraint System) ECU detects a communication interruption or physical disconnection of the Right Rear Side Impact Sensor (SIS).

This sensor mounts in the right C-pillar area or near the rear door frame to monitor collision acceleration signals from the right rear of the vehicle.

The SRS ECU sets this DTC if it fails to receive a valid signal from the sensor within the specified detection period, or if it detects circuit resistance outside the calibrated range (open circuit ∞Ω or short circuit 0Ω).

This safety-critical fault severely compromises rear occupant side-impact protection.

During a right-side collision, it may cause the side and curtain airbags to fail to deploy or deploy with incorrect timing.

4
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Sensor wiring harness connector is loose, disconnected, or has poor contact (common after accident repairs, failure to properly seat the connector after interior trim installation, or the plug vibrating loose from prolonged driving on rough roads).
  • 2Open or short circuit in the wiring harness (harness damage caused by frequent friction from rear passengers entering and exiting, compression by luggage, crushing in a vehicle accident, or rodent chewing)
  • 3Internal sensor fault (accelerometer element aging, cracked internal solder joints, moisture ingress, or physical impact damage resulting in no signal output)
  • 4Abnormal resistance in the communication circuit between the SRS ECU and the sensor (circuit oxidation or loose connector causing signal attenuation or interference)
  • 5Water intrusion into the connector during vehicle wading or washing causes pin oxidation and corrosion, resulting in high resistance and poor contact.
What To Do
  • 1
    Safety preparation: Switch the vehicle to OFF, disconnect the battery negative terminal, and wait at least 3 minutes to completely discharge the SRS system capacitors and prevent accidental airbag deployment.
  • 2
    Fault Confirmation: Use the BYD dedicated diagnostic tool (VDS2000/VDS6000) to read fault codes. Confirm B167A is a Current DTC rather than a history DTC. Check for other SRS-related DTCs (such as B1675, B1676, etc.).
  • 3
    Physical inspection: Remove the right rear C-pillar trim panel or rear seat side trim panel (depending on vehicle model), locate the right rear side impact sensor (usually marked SRS-SIS-RR or similar), and visually inspect the connector for looseness, disconnection, water ingress, or oxidation.
  • 4
    Circuit measurement: Disconnect the sensor connector. Use a multimeter to measure the wiring harness side for reference voltage (typically 5V±0.25V), ground wire continuity (<2Ω), and signal wire continuity. Also measure the sensor body resistance (normal range approximately 2-5kΩ; refer to the vehicle repair manual for specific values).
  • 5
    Wiring harness repair: If the wiring harness has an open circuit, short circuit, or oxidized connector, repair the wiring harness (solder and insulate with heat-shrink tubing), clean the connector contacts (using electrical contact cleaner), and replace the connector if necessary.
  • 6
    Component replacement: If wiring harness measurements are normal but the fault persists, replace the right rear side impact sensor (Note: Verify the part number matches for some models. During installation, point the arrow toward the front of the vehicle).
  • 7
    System reset: Reconnect all connectors, connect the battery, and clear the fault code. Turn the ignition switch to the ON position. Verify the SRS warning light turns off after 6 seconds. Use the diagnostic tool to confirm B167A transitioned to a history fault or cleared.
Real-World Cases
BYD DTC AI Analysis

BYD Song MAX: Loose connector after accident repair

✓
2019 Song MAX. Following accident repair to the right rear wing, the airbag warning light remained constantly on. Scanned with VDS and retrieved DTC B167A (current fault). Removed the right rear C-pillar trim and discovered the side impact sensor connector had not fully seated after the body repair, sitting partially dislodged and causing poor contact. Reinserted the connector until the locking tab clicked, secured the wiring harness with cable ties to prevent it working loose again, cleared the fault codes, and the SRS light went out. Fault resolved.
BYD DTC AI Analysis

Water wading caused sensor connector oxidation on a BYD Yuan EV.

✓
2019 Yuan EV. Airbag warning light came on after driving through floodwaters in heavy rain. Scan tool showed current fault code B167A. Inspection found poor sealing of the right rear sill wiring harness grommet. Water ingress caused severe oxidation and blackening of the pins inside the side impact sensor connector (white 2-pin connector), with green copper corrosion present. Cleaned the connector contacts thoroughly using electronic cleaner, applied dielectric grease (insulating silicone grease), replaced the grommet and resealed. Cleared the fault.
BYD DTC AI Analysis

BYD Tang DM wiring harness chafed through after prolonged wear, open circuit

✓
2021 Tang DM. At 50,000 km the SRS warning light illuminated intermittently, and DTC B167A appeared intermittently. Disassembly found the wiring harness on the inner side of the right rear door frame seal had rubbed against a metal bracket edge from repeated door operation, damaging the insulation. Three internal copper wires had broken completely, with only a few strands still making contact. Cut out the damaged section, soldered in extension wires, applied double-layer heat-shrink tubing, and rerouted the harness away from the sharp edge. Fault fully resolved.
BYD DTC AI Analysis

BYD Qin Pro sensor internal fault

✓
2020 Qin Pro, no accident history. Airbag warning light suddenly came on. Diagnostic scanner read current fault B167A. Checked the connector — secure. Measured harness supply voltage: 5V (normal). Ground normal, continuity normal. Diagnosed as internal accelerometer or conditioning circuit fault in the sensor. Replaced the right rear side impact sensor (part number must match VIN). Cleared fault codes and performed SRS self‑test; warning light went out, system returned to normal.
Other Atto 8 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.