AU
B167C00

DTC B167C00 indicates the Right Rear Side Impact Sensor in the Supplemental Restraint System (SRS) detects an internal functional fault — Seal U

Safety System

DTC B167C00 indicates the Right Rear Side Impact Sensor in the Supplemental Restraint System (SRS) detects an internal functional fault.

The sensor typically mounts in the vehicle C-pillar or right rear quarter panel area to monitor collision acceleration on the right rear side.

The SRS control module sets this fault code when the sensor experiences an internal circuit fault, communication interruption, or abnormal signal.

This fault may prevent the right rear side airbag or curtain airbag from deploying normally during a side impact, severely compromising passive safety performance.

It does not directly affect normal vehicle driving functions.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Damage or aging of the sensor body internal circuit causes abnormal signal output.
  • 2Poor contact, oxidation, or terminal back-out at the sensor wiring harness connector; repeated bending easily damages the wiring harness inside the C-pillar trim.
  • 3Improper sensor installation position or insufficient fixing bolt torque after rear collision repairs, causing reduced sensor sensitivity.
  • 4Open circuit, short to ground, or short to power in the communication line between the SRS control module and the sensor.
  • 5Sensor incorrectly configured or calibrated (sensor calibration procedure not performed after replacing parts).
What To Do
  • 1
    Use the BYD VDS diagnostic tool to read and confirm the DTC status. Check for related DTCs (such as B167B11, B167D00). Record the freeze frame data, then attempt to clear the DTC and observe if the fault is intermittent.
  • 2
    Remove the right rear C-pillar trim panel and inspect the side impact sensor for physical damage, cracks, or water stains. Verify correct sensor installation direction and confirm the fastening torque meets the standard (usually 8-10 N·m).
  • 3
    Disconnect the 12V battery negative terminal and wait 3 minutes. Unplug the sensor connector and inspect the pins for oxidation or backing out. Test the wiring harness side: with the ignition switch ON, the reference voltage must be 5V, and the ground wire resistance must be less than 1Ω.
  • 4
    Use an oscilloscope to check the sensor signal waveform. The sensor normally outputs a 2.5V reference voltage at rest and produces a corresponding voltage change during collision simulation. A fixed 0V or 5V output indicates an internal sensor fault.
  • 5
    Check the continuity and insulation of the communication line (usually the PWM signal line) from the SRS ECU to the sensor. Measure the wiring harness resistance to verify it is less than 2 Ω. Verify the insulation resistance to ground/power supply is greater than 10 MΩ.
  • 6
    If diagnostics confirm a sensor fault, replace the sensor with a genuine part (the part number must match the vehicle model; the Qin Pro series typically uses SAS-3643X0 or a newer version). After installation, perform the 'Airbag Sensor Calibration' procedure.
  • 7
    After completing the repair, use VDS to perform an SRS system self-check and confirm no fault codes are present. Perform a simulated collision test (using the special tool) to verify normal sensor response.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin Pro DM: Worn right rear collision sensor wiring harness causing intermittent warning.

✓
Airbag warning light illuminated intermittently. DTC B167C00 stored. Inspection found the wiring harness inside the right rear C-pillar had worn insulation from repeated rear door operation, causing copper wires to intermittently short to earth. Replaced 30 cm of damaged wiring, added abrasion-resistant corrugated tubing for protection, and re-routed harness away from metal edges. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Incorrect sensor orientation after accident repair caused fault.

✓
The vehicle sustained scrape damage on the right rear. After the right rear quarter panel was replaced at an independent shop, the instrument cluster displayed a persistent airbag fault. Diagnosis found the right rear side impact sensor installed backward (arrow should point forward), causing incorrect axial sensing. Reinstalled the sensor in the correct orientation, tightened to the specified 9 N·m with a torque wrench, and performed system calibration. Fault cleared.
BYD DTC AI AnalysisFrom Chinese market (translated)

Internal short circuit in sensor due to water ingress

✓
After driving through water, the airbag warning light stayed on constantly. Found current fault code B167C00. Removed and inspected the right rear sensor; found internal water ingress and corrosion. Measured resistance below 100Ω, indicating a short circuit. Cause: Aged sensor seal allowed water to penetrate via capillary action through the wiring harness during water exposure. Replaced the sensor and waterproofed the wiring harness connector (applied conductive grease and waterproof tape). Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

SRS control module software false alarm update case

✓
Multiple Qin Pro vehicles reported DTC B167C00. The sensors and wiring harness tested normal. A BYD technical bulletin confirmed that early SRS control module software contained false diagnostic logic. Solution: Upgrade the SRS ECU software to V2.3 or higher. The fault code does not return after the upgrade; no hardware replacement required.
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]