AU
B1667-00

DTC B1667-00 indicates the airbag control unit (SRS ECU) detects a short to body ground in the signal circuit of the left side impact sensor (typically installed inside the left B-pillar reinforcement panel) — Seal U

Safety System

DTC B1667-00 indicates the airbag control unit (SRS ECU) detects a short to body ground in the signal circuit of the left side impact sensor (typically installed inside the left B-pillar reinforcement panel).

This sensor is typically a MEMS capacitive or piezoelectric accelerometer.

During normal operation, it returns a bias resistance of approximately 2.1-2.9 kΩ and a signal voltage of approximately 2.5 V to the ECU.

When wiring harness insulation breaks, water enters the connector, or the sensor shorts internally, the ECU detects a continuous voltage signal below 0.5 V (short-to-ground threshold) and triggers this DTC.

This fault disables the trigger threshold determination for the left side airbag and curtain airbag.

During a side collision, the airbags may fail to deploy promptly, or signal interference during normal driving may cause unintended deployment.

This is a highest-level safety fault.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Sensor wiring harness insulation damage causing a short to ground: common causes include underbody scraping, loose harness retaining clips causing the harness to rub against metal body edges, or harness damage from crushing during sill trim panel removal and installation.
  • 2Connector water ingress and corrosion: Poor sealing in the left B-pillar area, a blocked sunroof drain hose causing leaks, or direct high-pressure washing of the B-pillar causes connector terminal oxidation, resulting in a short to ground.
  • 3Internal damage to the sensor body: Severe vibration (e.g., improper removal and installation, or accidents) causes breakdown of the internal piezoelectric element or circuit board, or electronic components fail due to aging after the sensor exceeds its 5-year service life.
  • 4Installation defects: deformed sensor mounting bracket (not straightened after collision repair), excessive tightening torque cracking the housing, or missing mounting spacer allowing the sensor housing to directly contact the vehicle body metal and cause a short circuit.
  • 5Internal SRS ECU fault: Damage to the ECU internal sampling circuit causes a false short to ground. Rule out by substitution (occurrence rate approx. 5-10%).
What To Do
  • 1
    Safety Preparation: Wear insulated gloves, disconnect the 12V low-voltage battery negative terminal, and wait at least 90 seconds to fully discharge the SRS system capacitors (for new energy vehicles, confirm the high-voltage system READY light is off).
  • 2
    Fault Confirmation: Use the BYD dedicated diagnostic tool (VDS or ED400) to read SRS system fault codes, confirm B1667-00 is the current fault code, and record freeze frame data (ambient temperature, voltage value).
  • 3
    Physical inspection: Remove the left B-pillar lower trim panel and sill trim panel. Visually inspect the wiring harness corrugated conduit for damage and connector KG10 (or K05, depending on vehicle model) for signs of water ingress (green copper corrosion, white crystalline deposits).
  • 4
    Circuit isolation check: Disconnect the left side impact sensor connector. Use a multimeter to measure the resistance between the wiring harness side terminal (KG10-12 or corresponding pin) and body ground. Normal value: >1 MΩ. If the resistance is <1 Ω, this confirms a short to ground. Trace the wiring to locate the damaged point.
  • 5
    Sensor body inspection: Measure the resistance between the sensor-side terminals. The normal value is 2.1-2.9 kΩ (refer to the vehicle repair manual for exact specifications). Replace the sensor if the resistance is close to 0 Ω or infinite.
  • 6
    Connector repair: If terminals are oxidized, clean with electronic contact cleaner and apply conductive grease. If the locking tab is damaged or a terminal has backed out, replace the entire connector assembly and verify the waterproof sealing ring is intact.
  • 7
    Wiring harness repair: Wrap the damaged wiring harness with double-layer heat-shrink tubing, adjust the harness routing to avoid contact with sharp metal edges, and secure the retaining clips to ensure no stress.
  • 8
    Replace the sensor (if necessary): Use genuine parts (e.g., part number BYD-3636010 series). Verify the mounting surface is flat and undeformed. Tighten to the standard torque of 8 N·m (do not use an impact wrench). Note the sensor installation direction mark (typically the 'UP' arrow points to the roof or 'F' points to the front of the vehicle).
  • 9
    System reset: Reconnect the battery. Turn the ignition on without starting the vehicle. Verify the SRS warning light turns off after 6 seconds. Use the diagnostic tool to clear the fault code. Perform 'SRS system self-learning' or 'crash sensor zero-point calibration' (required on some models).
  • 10
    Verification test: Perform a road test for at least 30 minutes, including bumpy roads. Use a diagnostic tool to read the data stream and confirm the left crash sensor signal voltage remains within 2.3-2.7V without fluctuation.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Poor connector contact damaged the sensor on BYD Qin Pro DM

✓
The airbag warning light on the instrument panel stayed on. Read DTC B1667-00. Inspection revealed the vehicle had recently undergone left door sheet metal and paint repair. Removing the B-pillar trim during that work left the left side impact sensor connector not fully seated. Reconnecting it cleared the fault temporarily, but it returned the next day. Further measurement showed the sensor's internal resistance had abnormally dropped to 1.2 kΩ (standard 2.3 kΩ). We determined the loose connector caused an intermittent short circuit; long-term poor contact overheated and damaged the sensor's internal circuit. Replaced the left side impact sensor (part number: BYD-3636010), installing it on the B-pillar reinforcement plate at the specified torque of 8 N·m. Fault completely resolved.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song Plus EV door sill wiring harness damaged, short to ground

✓
After turning the ignition on, the airbag warning light stayed on. The scan showed DTC B1667-00. The data stream showed the left collision sensor voltage signal was 0V (normal 2.5V). I disconnected the sensor connector inside the left B-pillar and measured terminal KG10-12 at the harness side. Resistance to ground was less than 1Ω, confirming a short to ground. I traced the harness and found a retaining clip had compressed the wiring inside the left sill trim, damaging the insulation and exposing the copper wire to the body. Repair: I re-wrapped the damaged harness with double-layer heat shrink tubing for insulation, rerouted the harness to avoid the clip, and cleared the fault codes. The SRS system returned to normal.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Han EV connector terminal pin backed out causing intermittent short circuit

✓
The airbag warning light came on intermittently and sometimes went out automatically. The scan tool retrieved historical DTC B1667-00 and current DTC B1666-00 (open circuit), indicating an intermittent fault. Inspection found minor damage to the left crash sensor connector latch. Wiggling the wiring harness caused resistance between terminals KG10-12 and K05(A)-2 to fluctuate between 0.5Ω and infinity. The backed-out terminal pin caused an intermittent short to ground. Replaced the left crash sensor harness connector assembly, ensured correct terminal spring tension, fully seated the connector, and locked the latch. Road-tested over rough surfaces; the fault did not reoccur.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

Incorrect sensor installation after accident repair on a BYD Destroyer 05

✓
After a left side collision, an outside repair shop replaced the left front door and B-pillar trim. Following the repair, the airbag warning light stayed on and DTC B1667-00 could not be cleared. Inspection found the left side impact sensor was the old unit removed during the accident. It had visible cracks but had not been replaced; resistance measured 0Ω (internal short). Further inspection revealed slight deformation at the B-pillar inner panel mounting point, causing the sensor installation angle to exceed 5° (workshop manual requires ±5°). The mounting bolt torque was excessive (measured 15 N·m, standard 8 N·m), which cracked the sensor housing. Solution: Straightened and repaired the B-pillar inner panel mounting surface. Replaced the sensor and installed it to standard torque and orientation. Fault resolved.
Original source ↗
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]