AU
B167800

This DTC indicates the SRS electronic control unit detects a functional fault in the Left Rear Side Impact Sensor (mounted in the lower left B-pillar or inside the left rear quarter panel) — Seal 6 EV

Safety System

This DTC indicates the SRS electronic control unit detects a functional fault in the Left Rear Side Impact Sensor (mounted in the lower left B-pillar or inside the left rear quarter panel).

Specifically, the ECU receives no valid acceleration signal, the signal exceeds the normal threshold (typically 0.5-4.5V), or the system detects an open or short circuit.

This sensor monitors side-impact acceleration on the left rear of the vehicle.

The ECU uses this signal to determine whether to deploy the left curtain airbag and rear side airbag.

When this fault occurs, the system enters fail-safe mode, illuminates the airbag warning light, and disables the related side airbags, significantly increasing the risk of occupant protection failure during a side collision.

The B167800 fault code on the Seal 6 EV indicates a malfunction in the Left Rear Side Impact Sensor, which monitors side-impact acceleration to control the left curtain and rear side airbags. Severity is medium. Common causes include internal sensor damage or water ingress corroding the B-pillar wiring connector. This disables the affected airbags, increasing injury risk during a side collision. Visit an authorised dealer for repair. Typical repair cost data is available from 3 recorded cases.
3
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1Damaged piezoelectric accelerometer or signal processing IC inside the sensor body, causing output signal drift or no signal.
  • 2Water ingress and oxidation in the wiring harness connector at the base of the left B-pillar (common after car washing or wading), causing increased contact resistance or a short circuit in the signal wire.
  • 3Body wiring harness broken at the B-pillar hinge bend, or improper harness routing after accident repairs, causing an open circuit.
  • 4Loose or detached sensor mounting bracket, or external impact to the sensor, causing the internal inertial measurement unit to lose calibration.
  • 5SRS ECU internal sampling circuit fault (uncommon; confirm after ruling out wiring faults)
What To Do
  • 1
    Use the BYD VDS3000 diagnostic tool to read complete fault codes and freeze frame data. Check for accompanying sub-fault codes such as B167711 (short to ground) or B167712 (short to power supply). Record the vehicle speed and ambient temperature at the time of the fault.
  • 2
    Disconnect the negative battery terminal. Wait at least 90 seconds for the SRS capacitor to fully discharge. Remove the left B-pillar lower trim panel and the left rear door sill trim panel. Visually inspect the crash sensor for cracks and verify the installation torque marks align (standard torque is typically 8-10 N·m).
  • 3
    Disconnect the sensor 2-pin connector. Check the terminals for oxidation, backed-out pins, or signs of water ingress. Clean with electrical contact cleaner and apply conductive grease.
  • 4
    Measure wiring harness voltage: With ignition ON, signal wire to ground voltage should be approximately 2.5V (reference voltage), and power wire voltage should be 12V (battery voltage). Measure insulation: Verify signal wire to ground resistance is greater than 1MΩ.
  • 5
    If the wiring is normal, remove the sensor and measure its static resistance (typically 2.0-3.0 kΩ; refer to the repair manual for exact values). Lightly tap the sensor while monitoring the resistance. If the resistance does not change, the sensor has internal damage.
  • 6
    Replace the left rear side impact sensor (Note: On some high-spec models, execute the 'Replace Crash Sensor' configuration procedure in VDS to write the sensor serial number). Restore the wiring harness connection and verify the waterproof rubber seal is intact.
  • 7
    Reconnect the battery, clear the fault code, and perform the SRS system self-check (approximately 10 seconds). Confirm the warning light turns off. Use the dedicated diagnostic tool to read the live data stream. Lightly tap near the sensor mounting position and verify the acceleration signal changes.
  • 8
    Perform a road test on a rough road to confirm the intermittent fault code does not recur. Finally, check and clear all history fault codes.
Real-World Cases
BYD DTC AI Analysis

Left rear sensor intermittently reporting fault after wading

✓
2018 Qin Pro DM. Owner reported the airbag warning light would intermittently come on during rain or after washing. VDS scan showed active code B167800. Removed the left B-pillar lower trim, found water inside the sensor connector and green copper corrosion on the pins. Traced to deteriorated door seals allowing water ingress along the wiring harness. Cleaned harness terminals, replaced the sensor (internally moisture-damaged), rewrapped the harness and adjusted the waterproof tape position. Fault resolved.
BYD DTC AI Analysis

Open circuit in wiring harness following accident repair caused fault

✓
2019 Qin Pro (petrol). After a left rear side collision, an independent workshop repaired the vehicle. After delivery, the airbag light stayed on. Diagnosis found current DTC B167800 and no voltage at the sensor terminals. Tracing the wiring harness revealed a clamping plate had crushed it during the inner B-pillar repair, breaking the power wire. Repair involved soldering and heat-shrinking the harness, rerouting the wiring to avoid the crush point, and clearing the fault code. The system returned to normal.
BYD DTC AI Analysis

Sensor ageing caused signal drift

✓
The SRS warning light suddenly came on in a 2018 Qin Pro DM with 120,000 km and no collision history. The diagnostic scan tool displayed code B167800. Checked the wiring harness and connectors and found no faults. Measured the sensor's static resistance and found it normal. However, oscilloscope monitoring revealed abnormal noise in the signal output. Determined this was due to internal accelerometer degradation in the sensor. Replaced the left rear side impact sensor and performed the sensor matching procedure. Fault resolved.
Other Seal 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV 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.