AU
B167B-00

This DTC indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance connection (short to ground) between the right rear side impact sensor (SIS) signal circuit and body ground (GND) — Seal U

Safety System

This DTC indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance connection (short to ground) between the right rear side impact sensor (SIS) signal circuit and body ground (GND).

BYD SRS architecture typically uses piezoelectric or acceleration-type side impact sensors.

These sensors mount inside the right rear door, behind the C-pillar trim panel, or beside the rear seat to monitor lateral impacts to the right rear of the vehicle.

When the sensor signal wire shorts to ground, the ECU continuously receives a low-level signal near 0V and cannot correctly identify actual collision deceleration signals.

This causes the following: 1) the right rear airbag (side airbag/curtain airbag) may fail to deploy during a side impact; 2) the system enters fail-safe mode, illuminates the airbag warning lamp, and may disable the entire airbag system.

Cycling the ignition typically cannot clear this hard fault.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Internal integrated circuit fault in the right rear side impact sensor causes a breakdown short circuit between the signal output terminal and the sensor housing (ground).
  • 2The sensor wiring harness chafes at the door hinge, inside the corrugated harness sleeve, or at the floor harness grommet, and the damaged wire insulation contacts the vehicle body metal frame.
  • 3Vehicle wading, a blocked and leaking sunroof drain tube, or direct spray from a high-pressure washer causes water ingress into the sensor connector (usually located below the C-pillar or inside the sill beam), resulting in an electrolytic short circuit between the pins or a short to ground.
  • 4After accident repairs or interior trim removal/installation, missing wiring harness retaining clips allow the seat rail, seat belt mounting bolt, or metal edge of the interior trim panel to pinch and damage the wiring harness, causing a short to ground.
  • 5A deformed sensor mounting bracket or over-tightened retaining bolts cause the sensor metal housing to directly contact the body ground terminal, shorting the internal circuit to ground through the housing.
What To Do
  • 1
    Safety preparation: Shift the vehicle into P, apply the parking brake, turn off the ignition, disconnect the 12V battery negative terminal, and wait at least 90 seconds to fully discharge the SRS system backup power supply and prevent accidental airbag deployment.
  • 2
    Fault confirmation: Use the BYD dedicated diagnostic tool (VDS or ED400) to read fault codes. Confirm B167B-00 is a current fault (Active). Record freeze frame data and check for other accompanying crash sensor fault codes.
  • 3
    Locate the component: Remove the right rear door trim panel or right rear C-pillar trim panel and find the right rear side impact sensor (usually a black or yellow rectangular component with a 2-pin or 3-pin connector, marked with an 'SIS' or 'Airbag' label).
  • 4
    Visual inspection: Check the sensor housing for cracks, physical damage, or signs of corrosion. Check the connector for looseness, broken locking tabs, backed-out terminals, or green oxidation.
  • 5
    Sensor body inspection: Disconnect the connector. Use a multimeter to measure the resistance between the power supply/signal pins on the sensor side and the sensor metal housing. The reading should be open circuit (infinite). If the resistance is less than 1Ω, the sensor has an internal short circuit. Replace the sensor.
  • 6
    Harness continuity check: Keep the sensor disconnected. Measure the resistance between the harness-side signal wire and ground (should be infinite). Measure the resistance between the signal wire and the ground wire (should be infinite). If continuity exists, inspect along the harness routing. Focus on the harness sleeve at the door hinge (prone to damage from repeated bending) and the section where the floor harness passes under the B-pillar.
  • 7
    Repair procedure: If the wiring harness is damaged, cut out the damaged section. Repair by soldering a high-temperature automotive wire of the same cross-sectional area (0.5 mm² or larger recommended). Wrap the outer layer with two layers of waterproof insulating tape (PVC + cloth-backed). Add corrugated conduit protection if necessary. Maintain a clearance of more than 20 mm between the repaired wiring harness and the vehicle body metal.
  • 8
    Restoration and verification: Reconnect the sensor and listen for an audible 'click' to confirm the connector locks. Reconnect the battery, clear the fault code, and turn the ignition switch to the ON position. Verify the instrument panel airbag warning light turns off after 6 seconds. Read the data stream using a diagnostic tool. Lightly tap the vehicle body around the sensor and confirm the signal voltage changes normally within the 0.5-4.5V range.
  • 9
    Final check: Perform the SRS system Ignition Cycle Test, verify the fault code does not return, and reinstall all interior trim panels.
Real-World Cases
BYD DTC AI Analysis

Water ingress into sensor connector caused short circuit after driving through water

✓
The owner of a 2019 BYD Qin EV450 reported the airbag warning light on the dashboard stayed on after driving through heavy rain and flood water. A VDS diagnostic scan retrieved DTC B167B-00 (current fault). The technician removed the right rear sill trim panel and found significant water in the side impact sensor connector below the C-pillar; the pins had green copper oxide corrosion. Tracing the root cause, the technician found the right rear sunroof drain hose connector had detached, allowing rainwater to run down the C-pillar into the sill area. The technician cleaned the connector pins with electronic contact cleaner, dried them, applied conductive protective grease, reconnected the connector, wrapped it with waterproof tape, and repaired the drain hose connection. After clearing the fault codes, multiple water spray tests confirmed the fault did not return.
BYD DTC AI Analysis

Wiring harness crushed by seat rail following accident repair

✓
A 2017 BYD Qin 100 had been in a right-rear side collision. After repairs at an independent workshop, an intermittent DTC B167B-00 appeared. Diagnosis showed the fault occurred when the vehicle hit bumps. Removing the rear seat revealed that during reinstallation, the technician had failed to properly secure the side impact sensor wiring harness (located on the right floor), leaving it trapped beneath the seat rail. Repeated seat adjustments caused the rail edge to chafe through the harness insulation, exposing copper wires that contacted the bodywork and shorted to ground. Repair: Cut out the damaged section, soldered and insulated the wires, rerouted the harness, and secured it in the floor wiring channel using OEM clips to maintain clearance from the seat rail.
BYD DTC AI Analysis

Replaced sensor due to internal aging and short circuit.

✓
A 2018 BYD E1 with 68,000 km and no accident history. The airbag warning light came on. The scan tool pulled code B167B-00; cleared, but it returned after a few kilometres. Disconnected the sensor, measured resistance between terminals and housing: it fluctuated between 0.5 and 50 Ω (normal: open circuit). Disassembled the sensor and found electrolyte on the internal PCB—the internal gel in this piezoelectric sensor had aged. Repair: replaced with genuine right rear side impact sensor (part number matched to VIN, typically BYD-specific). Torqued to spec (8–10 Nm) to avoid housing deformation. Fault cleared permanently.
BYD DTC AI Analysis

Aftermarket audio installation damaged the wiring harness

✓
A 2020 BYD E1. The owner retrofitted the rear door speakers himself, using self-tapping screws to secure them. The screws were too long, penetrating the door trim panel and piercing the side impact sensor wiring harness (inside the door wiring loom), shorting the signal wire to ground. Diagnosis found DTC B167B-00 and no sound from the right rear door speaker. Repair: removed the aftermarket speaker, extracted the penetrating screw, repaired the damaged harness (3 wires affected, 1 being the sensor signal line), and restored the factory wiring. Advised the owner to revert to the original audio configuration or have compliant modifications carried out at an authorized workshop.
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.