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) — Seal U

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.

The B167A fault code on the Seal U indicates a communication failure or disconnection with the Right Rear Side Impact Sensor, compromising rear occupant side-impact protection and potentially preventing airbag deployment during collisions. Severity is medium. Common causes include loose wiring connectors or harness damage from friction or accidents. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available based on 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Sensor wiring harness connector is loose, disconnected, or has poor contact (common after accident repairs, improper seating after interior trim removal and installation, or plug loosening from prolonged driving on rough roads).
  • 2Wiring harness open or short circuit (harness damage resulting from frequent friction during rear passenger entry and exit, crushing by luggage, vehicle accidents, or rodent chewing)
  • 3Internal sensor body 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 car 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 fully discharge the SRS system capacitors and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use the BYD dedicated diagnostic tool (VDS2000/VDS6000) to read the fault codes. Confirm B167A is a current fault (Current DTC) rather than a history DTC. Check for accompanying SRS-related fault codes (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 and use a multimeter to measure the wiring harness side: reference voltage (typically 5V±0.25V), ground circuit continuity (<2Ω), and signal circuit continuity. Also measure the sensor resistance (normal range approximately 2-5kΩ; refer to the vehicle repair manual for exact specifications).
  • 5
    Wiring harness repair: If the wiring harness has an open or short circuit, or the connector is oxidized, 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 on applicable models. Install the sensor with the arrow pointing 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 and check if the SRS warning light turns off after 6 seconds. Use a 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 Seal U Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U overview →
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.