AU
B167A-00

DTC B167A-00 indicates the airbag control unit (SRS ECU/ACU) detects an open circuit, abnormal resistance, or complete loss of communication in the Right Rear Side Impact Sensor (RR-SIS) circuit — Seal U

Safety System

DTC B167A-00 indicates the airbag control unit (SRS ECU/ACU) detects an open circuit, abnormal resistance, or complete loss of communication in the Right Rear Side Impact Sensor (RR-SIS) circuit.

This sensor typically mounts in the right rear C-pillar, D-pillar, or inside the right rear quarter panel to monitor collision acceleration signals from the right rear of the vehicle.

The ACU sets this DTC if it fails to receive a valid signal from the sensor within a predetermined time, or if it detects circuit resistance exceeding the threshold (typically >10kΩ or an open circuit).

This fault forces the right side airbag system (side airbag/side curtain airbag) into fail-safe mode.

The system may fail to deploy correctly during a side impact, severely compromising occupant protection.

The front airbag system typically remains operational.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Sensor plug loose or disconnected: The right rear side impact sensor is located behind the C-pillar or D-pillar trim panel. Failing to connect the sensor plug correctly after accident repairs, interior trim removal and installation, or rear quarter panel sheet metal repairs, or a broken plug retaining clip causing poor contact.
  • 2Wiring harness open circuit or chafing: The harness from the ACU to the right rear sensor routes through the right B-pillar, C-pillar sill, or under the rear seat. Crushing by the seat adjustment mechanism, water ingress corrosion, rodent damage, or accident deformation can break the internal copper conductors.
  • 3Sensor body internal fault: A damaged internal piezoelectric accelerometer element or open internal circuit prevents the sensor from generating a valid crash signal or interrupts communication.
  • 4Poor ground or abnormal power supply: Poor contact in the sensor power supply circuit (usually 5V reference voltage) or ground circuit prevents the ACU from recognizing the sensor.
  • 5ACU interface fault: Damage to the airbag control unit interface circuit for the right rear side impact sensor (e.g., burnt sampling resistor or A/D converter fault). This condition is relatively rare.
What To Do
  • 1
    Safety preparation: Set the vehicle to OFF, disconnect the low-voltage battery negative terminal, and wait at least 90 seconds (120 seconds for some models) to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Location and removal: Refer to the vehicle repair manual (E1/Qin series). Remove the right rear C-pillar trim panel or right rear fender liner, and locate the right rear side impact sensor (usually a black or yellow 2-pin or 3-pin connector).
  • 3
    Visual inspection: Verify the sensor connector is fully inserted and the locking tab is in place. Check the terminals for push-out, oxidation, water ingress corrosion (white or green oxides), or bent pins.
  • 4
    Circuit continuity check: Disconnect the ACU connector (observe anti-static precautions) and the sensor connector. Use a multimeter to measure the continuity resistance between both ends of the sensor wiring harness (ACU end and sensor end). Standard value: <1Ω. Measure the insulation resistance from the wiring harness to ground and to the power supply. Standard value: >10MΩ (to rule out a short circuit).
  • 5
    Sensor resistance check: Remove the sensor and measure its internal resistance (reference value is typically 2.0-3.0 kΩ; refer to the workshop manual for exact specifications). Infinite resistance indicates an internal open circuit; 0 Ω or an extremely low reading indicates an internal short circuit.
  • 6
    Swap test (key step): Swap the right rear and left rear side impact sensors. Power on the vehicle and read the fault code. If the fault code changes to B1679-00 (left rear sensor fault), the original sensor is faulty. If the fault code remains B167A-00, the fault is in the wiring harness or ACU.
  • 7
    Repair and replacement: Repair damaged wiring harnesses using solder and heat-shrink tubing (do not simply wrap wires). Replace damaged sensors (match part numbers; some models require differentiating between domestic and imported supplier parts). Apply conductive grease to connectors to prevent oxidation.
  • 8
    System reset and verification: Restore all connections and turn on the power. Use the BYD dedicated diagnostic tool (VDS2000/3000) to perform "SRS system self-check" or "crash sensor configuration". Clear the fault code, then confirm B167A-00 does not return and the airbag warning light turns off.
Real-World Cases
BYD DTC AI Analysis

Qin EV450 sensor connector not fully seated after accident repair

✓
A 2018 Qin EV450 suffered scrape damage to the right rear quarter panel and was repaired with panel beating and respraying at a non-authorised shop. After the repair, the airbag warning light on the instrument panel stayed on. Technicians used a VDS2000 scan tool to retrieve DTC B167A-00 (Right Rear Side Collision Sensor Not Connected). They removed the right rear C-pillar interior trim and found that the right rear side collision sensor (located at the base of the C-pillar) had been removed during the accident repair. When reinstalling the sensor, the repairer did not hear the locking click, so the connector was not fully seated and caused a loose connection. The technicians reseated the plug, confirmed the locking tab was fully engaged, cleared the fault codes, and ran an SRS self-test. The system passed and the fault was resolved.
BYD DTC AI Analysis

Water ingress caused sensor corrosion and open circuit on an E1 electric vehicle.

✓
A 2019 BYD E1 waded through water approximately 40 cm deep; afterwards, the airbag warning light came on. The technician retrieved DTC B167A-00. Inspection of the right rear side impact sensor (near the right rear fender liner) found water marks and green copper corrosion inside the connector; the connector seal had deteriorated and failed. The sensor body resistance was 2.4 kΩ (normal), but resistance across the connector terminals read infinite (open circuit). The technician cleaned the terminals, applied electronic contact cleaner, replaced the waterproof seal, and rewrapped the connection with waterproof tape, clearing the fault. The technician also recommended checking the waterproofing of other SRS components on the same side.
BYD DTC AI Analysis

Qin 100 rear seat wiring harness crushed by seat rail, causing open circuit

✓
2017 BYD Qin 100. The customer reported the airbag warning light occasionally flashed on bumpy roads, then stayed on constantly. Retrieved intermittent DTC B167A-00. Inspected the right rear side impact sensor connector – connection normal. Measured sensor resistance – normal. Removed the rear seat and found the wiring harness pinched at the right rear seat slide rail mounting bracket, with damaged insulation and partially broken copper wires causing an intermittent open circuit. Repaired the damaged wiring: cut out the damaged section, re-soldered the wires, and insulated with double-layer heat-shrink tubing. Rerouted the wiring to clear the seat movement path. Fault completely resolved.
BYD DTC AI Analysis

Piezoelectric element inside sensor failed.

✓
A 2017 Qin EV300 with no accident history suddenly showed an airbag warning light. Read DTC B167A-00; could not clear it. Checked wiring continuity — normal. Connectors had no oxidation. Swapped left and right rear side impact sensors, and the DTC moved to the left side (B1679-00), confirming an internal fault in the original right sensor. Replaced the right rear side impact sensor (part number: ...matched to vehicle model). Performed the 'replace impact sensor' configuration procedure with a diagnostic scanner (some models require sensor ID writing or calibration). Fault resolved.
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.