AU
B167600

This DTC indicates the airbag control unit (SRS ECU) detects a communication loss or open circuit between the Left Rear Side Impact Sensor (typically installed on the left rear quarter panel or C-pillar area) and the main control unit — Seal U

Safety System

This DTC indicates the airbag control unit (SRS ECU) detects a communication loss or open circuit between the Left Rear Side Impact Sensor (typically installed on the left rear quarter panel or C-pillar area) and the main control unit.

Specifically, during the ignition ON self-check or continuous monitoring while driving, the ECU detects the sensor circuit resistance exceeds the normal range (exhibiting high resistance or an open circuit) and fails to receive a valid acceleration signal.

This fault causes the SRS system to disable deployment of the left side airbag and side curtain airbag.

In a left-side collision, these airbags may fail to deploy, severely compromising passive safety performance.

The vehicle drive system remains unaffected.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Loose sensor wiring harness connector or poor contact (common after vehicle wading, severe vibration, or improper seating after repairs).
  • 2Internal open circuit in the left rear side impact sensor (component aging, broken internal circuit board, or corrosion from water ingress)
  • 3Wiring harness open circuit or damaged insulation (long-term chafing against the left rear door frame weatherstrip, or a detached harness retaining clip causing the harness to stretch and break)
  • 4Deformed sensor mounting bracket or poor ground circuit (affecting the signal reference voltage circuit)
  • 5SRS ECU internal detection circuit fault (very rare; rule out by substitution).
What To Do
  • 1
    Use a BYD VDS2000 or Launch X431 diagnostic tool to read all DTCs and freeze frame data. Confirm B167600 is a current fault code and record the vehicle status at the time of the fault.
  • 2
    Turn off the ignition, disconnect the negative battery terminal, and wait at least 3 minutes to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 3
    Remove the left rear C-pillar trim panel and the rear seat side trim panel. Locate the left rear side impact sensor (usually marked 'LR SIS', located above the left rear sill beam or on the lower C-pillar).
  • 4
    Visually inspect the sensor wiring harness connector (usually a 2-pin or 3-pin black plug) for looseness, broken locking tabs, backed-out terminals, or corrosion. Reconnect the connector and confirm it locks into place.
  • 5
    Disconnect the sensor connector and use a multimeter to measure the resistance between the sensor body terminals. The normal value is usually 2-3 kΩ (refer to the vehicle repair manual for exact specifications). If the reading is infinite, the sensor has an internal open circuit. Replace the sensor.
  • 6
    Keep the sensor disconnected and measure continuity between the harness-side connector and the SRS ECU (check the wire color, usually yellow/black or yellow/white). Check insulation to ground and repair any open or short circuits.
  • 7
    Inspect the wiring harness corrugated conduit for damage, focusing on contact points between the wiring harness and body sheet metal. Repair any chafing and re-secure the harness with cable ties. Maintain a safe distance from metal edges.
  • 8
    Reconnect all components and the battery, clear the fault code using the diagnostic tool, and perform an SRS system self-check (ensure the steering wheel is centered and the vehicle is level).
  • 9
    Perform a road test or use the diagnostic tool to run the 'Crash Sensor Active Test' (if supported). Confirm the fault code does not return and the instrument cluster airbag warning lamp turns off.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Left rear sensor connector loose on BYD E2 ride-hailing vehicle.

✓
A 2019 BYD E2 ride‑hailing car with 80,000 km had the airbag warning light on steady. The technician pulled DTC B167600. Inspection found the C‑pillar trim had been removed earlier for left rear door respraying, and the left rear side impact sensor’s 2‑pin connector was not fully seated, with the lock tab not engaged. Road vibration caused an intermittent open circuit. The technician reseated the connector, locked the tab, cleared the code, and the warning light went out.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin Pro DM: Sensor internal corrosion after wading

✓
2020 BYD Qin Pro DM. After driving through floodwater in heavy rain, the dashboard displayed 'Airbag System Fault'. The diagnostic tool read DTC B167600. Inspection revealed the left rear side impact sensor is located inside the left rear wheel arch, mounted low. Water ingress corroded the sensor's internal circuit board, causing an open circuit. The sensor resistance was infinite. Replaced the sensor, adjusted the mounting position (added a waterproof bracket), and cleaned and dried the wiring harness connector. Fault fully resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Wiring harness chafing against door seal caused intermittent open circuit

✓
2019 BYD Qin EV had an intermittent airbag warning light and sporadic code B167600. Inspection found the left rear side impact sensor harness interfering with the door seal below the B-pillar. Repeated door opening and closing wore through the insulation, partially fractured the copper wires, and caused an intermittent poor connection. Repaired the harness by cutting out the damaged section, soldering, and insulating with heat-shrink tubing. Re-routed the wiring away from the seal area and wrapped it with felt tape for protection. The fault has not returned.
BYD DTC AI AnalysisFrom Chinese market (translated)

Sensor not reconnected after accident repair caused function failure

✓
2018 Qin Pro petrol. After a left rear collision, a non-authorised workshop repaired the vehicle. After the repair, the airbag warning light stayed on constantly. Retrieved DTC B167600. Inspection found the left rear side impact sensor bracket had deformed during the accident. The repair technician had removed the sensor but failed to reconnect its plug, simply taping it loosely in place. Replaced the sensor bracket and fitted a new sensor. Connected and secured the wiring harness properly. Used a diagnostic tool for system configuration matching and cleared the fault.
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]