AU
B1670-00

DTC B1670-00 indicates an abnormally low-resistance connection between the right side impact sensor (SIS) signal circuit and body ground, resulting in a short to ground — Seal U

Safety System

DTC B1670-00 indicates an abnormally low-resistance connection between the right side impact sensor (SIS) signal circuit and body ground, resulting in a short to ground.

The BYD SRS (Supplemental Restraint System) architecture utilizes a piezoelectric or MEMS accelerometer for the right side impact sensor.

This sensor mounts inside the right B-pillar or the right front or rear door cavity and monitors side impact acceleration.

A short to ground prevents the SRS control unit (ACU) from receiving a valid analog acceleration signal (typically a 0.5-4.5V voltage signal).

Instead, the ACU receives a ground potential near 0V.

This condition triggers the ACU to enter fault protection mode, disable the right side airbag and curtain airbag deployment, and illuminate the airbag fault warning lamp.

If the short circuit occurs during an impact, it can cause unintended airbag deployment or failure to deploy, creating a serious safety hazard.

4
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Long-term bending at the door hinge wears the insulation on the right front or right rear door wiring harness, causing the signal wire (usually yellow) to contact the metal door frame and create a short to ground.
  • 2Internal seal failure in the right side impact sensor body allows rainwater or car wash fluid to penetrate the sensor and short-circuit the circuit board. This commonly results from incorrect installation of the waterproof sealing ring after accident repairs.
  • 3Water ingress or a damp environment oxidizes or corrodes the terminals in the sensor connector (2-pin or 3-pin plug) below the right B-pillar, causing a partial short circuit or a complete short to ground.
  • 4A front or right-side collision crushed and damaged the wiring harness, which went undetected. Technicians replaced only exterior parts during repair and failed to check SRS wiring harness insulation.
  • 5Internal fault in the SRS control unit (ACU) signal processing circuit causing a false short-to-ground detection (rare, <5% probability).
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal. Wait at least 90 seconds to ensure the SRS capacitor discharges completely and prevent accidental airbag deployment. Wear an anti-static wrist strap. Prepare a multimeter and insulated probes.
  • 2
    Locate the sensor: Refer to the vehicle repair manual (E1/Qin series) to confirm the right side impact sensor location (typically behind the right B-pillar lower trim panel or inside the front of the right front door cavity). Remove the corresponding interior trim panel to expose the sensor.
  • 3
    Disconnect the connector: Unplug the sensor connector and use a multimeter to measure the resistance across the sensor-side terminals (normal: infinite or specific internal resistance; short circuit: close to 0 Ω). If the sensor is normal, proceed to the next step.
  • 4
    Harness continuity test: Measure the signal wire-to-ground resistance from the sensor connector to the SRS ACU (usually located under the centre console or front compartment). If the resistance is <1 Ω, the circuit is shorted to ground.
  • 5
    Section-by-section troubleshooting: Inspect inside the wiring harness sleeve (rubber boot) at the door hinge. Peel back the sleeve and check the wires for wear and exposure. Also inspect the floor wiring harness below the B-pillar for crush damage from seat mounting bolts or corrosion from water-soaked carpets.
  • 6
    Repair verification: After repairing the damaged wiring harness (insulate using heat-shrink tubing) or replacing the sensor, reconnect all components and restore battery power. Use VDS or a Launch diagnostic tool to clear the fault code. Perform an SRS system self-check (turn the ignition switch ON and observe if the warning lamp turns off). Finally, perform a simulated crash signal test (use the special tool or lightly tap the sensor to verify the data stream).
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Right front door wiring harness chafed and shorted at the hinge

✓
A 2018 Qin EV450 with 80,000 km displayed 'Airbag System Fault' on the instrument cluster. DTC B1670-00 stored. Inspection found the right front door wiring harness rubber boot at the A-pillar hinge had deteriorated and split. The yellow signal wire insulation wore through where it contacted the door metal frame, shorting to ground. Replaced the entire right front door wiring harness (part number: BYD-SRS-LINE-RF), rewrapped with waterproof tape, and resolved the fault.
BYD DTC AI AnalysisFrom Chinese market (translated)

Sensor water ingress caused intermittent short circuit

✓
2019 E1. The airbag light came on after the vehicle drove through water. Scan tool showed DTC B1670-00. Inspection found water and green corrosion in the right side impact sensor connector, located below the right B-pillar. Root cause: the previous accident repair did not replace the sensor seal, so rainwater seeped down the B-pillar. Repair: cleaned connector terminals, replaced sensor (with seal), and applied dielectric grease to the connector. Fault did not recur.
BYD DTC AI AnalysisFrom Chinese market (translated)

Loose connector after accident repairs caused a short circuit.

✓
2017 Qin 100 sustained a right front collision. After the repair shop replaced the right front fender and door, the vehicle set DTC B1670-00 immediately upon startup. Inspection found that when the right front door interior trim panel was installed, the side impact sensor 2‑pin connector had not fully latched. The loose plug allowed the metal terminals to contact the door's metal bracket, shorting the signal wire to ground. After reconnecting the connector firmly and confirming the locking tab was fully seated, the fault code cleared and the system returned to normal.
BYD DTC AI AnalysisFrom Chinese market (translated)

SRS control unit false positive

✓
A Qin EV300 repeatedly set DTC B1670-00. Replaced the sensor and wiring harness, but the fault remained. Wiring harness continuity measured normal; sensor resistance within specification (approx. 1.8–2.2kΩ). Suspected an internal ACU circuit fault. Tried replacing the SRS control unit (requires synchronized configuration of VIN code and sensor parameters). Fault completely eliminated. This condition is commonly seen when vehicles are parked for long periods, causing capacitor aging inside the ACU.
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]