AU
B1670

DTC B1670 indicates an abnormally low-resistance connection (short to ground) between the right Side Impact Sensor (SIS) signal circuit and body ground (GND) — Atto 8

Safety System

DTC B1670 indicates an abnormally low-resistance connection (short to ground) between the right Side Impact Sensor (SIS) signal circuit and body ground (GND).

Electrically, this typically indicates damaged signal wire insulation contacting body metal, an internal connector short, or a sensor internal integrated circuit fault shorting the signal output terminal to the housing.

This fault causes the Airbag Control Unit (ACU) to continuously receive a false 'crash trigger' signal (voltage near 0V) or completely lose sensor communication.

Consequently, the ACU enters fail-safe mode, disabling the right airbag and side curtain airbag to prevent accidental deployment.

Additionally, if the system identifies the short circuit as a continuous crash signal on certain models, it may trigger unintended airbag deployment.

This fault constitutes a severe safety hazard and requires immediate repair.

3
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Right side impact sensor wiring harness wear: During long-term vehicle use, the sensor wiring harness inside the right B-pillar or sill trim rubs against body metal edges or retaining clips, damaging the insulation and shorting the copper core to body ground.
  • 2Connector water ingress or corrosion: Vehicle wading, a blocked sunroof drain, or improper car washing introduces moisture into the right crash sensor connector (usually located below the B-pillar or under the seat), causing a short circuit between pins or to ground.
  • 3Internal sensor body fault: Damage to the crash sensor piezoelectric element or signal processing circuit causes the signal output terminal to short to the sensor housing (ground).
  • 4Improper accident repair: After a right-side collision, improper routing or inadequate securing of the wiring harness during repair, or installing non-genuine parts that cause an electrical connector mismatch, triggers a short circuit.
  • 5SRS control unit (ACU) interface fault: In rare cases, damaged components in the ACU internal right-side sensor signal receiving circuit cause a false short-to-ground detection.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 3 minutes to discharge the airbag system energy storage capacitor and prevent accidental airbag deployment during repair.
  • 2
    Fault confirmation and freeze frame recording: Use the BYD VDS diagnostic tool to read the DTC B1670 status (current/history), record the freeze frame data (vehicle speed, timestamp, and sensor voltage values at the time of the fault), and confirm the specific right-side sensor location (front/center/rear).
  • 3
    Visual inspection: Remove the right B-pillar trim, sill trim, or seat (depending on vehicle configuration). Inspect the crash sensor for physical damage, the wiring harness for obvious crushing, cuts, or abrasion, and the connector for water ingress, oxidation, or deformed pins.
  • 4
    Electrical measurement verification: Disconnect the right side impact sensor connector and use a multimeter to measure the resistance between the signal wire (usually the positive wire) and body ground. The normal value is >1 MΩ (open circuit). A reading of 0-5 Ω confirms a short to ground. Simultaneously measure the resistance between the sensor output terminal and the housing to check for an internal short circuit.
  • 5
    Section-by-section wiring harness inspection: If the sensor is normal, strip the wiring harness sheath in sections from the sensor toward the ACU. Inspect body pass-throughs (firewall and B-pillar), harness clip locations, and bends to locate the damage.
  • 6
    Repair or replace: If the wiring harness is damaged, rewrap it with heat shrink tubing or electrical tape and reroute the harness to prevent further chafing. If the sensor has an internal short circuit, replace it with an OEM right side impact sensor (some models require sensor calibration or coding).
  • 7
    System verification: Restore all connections and reconnect the battery. Use VDS to clear the fault code. Perform the SRS system self-diagnosis procedure and confirm B1670 does not return. Finally, perform a road test or simulated vibration test to verify the fault is completely eliminated.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Song MAX B1670 – Right B-pillar wiring harness chafed, shorting to ground (Reference: similar SRS harness fault B2290)

✓
Symptom: The airbag warning light on the dash suddenly illuminated while driving a 2019 Song MAX. The VDS scan tool retrieved fault code B1670 (right side impact sensor short to earth). Diagnosis: Removed the right B-pillar trim and found the side impact sensor wiring loom had chafed against the retaining clip over time. The insulation had worn through, causing the copper wire to contact the bodywork. Measured signal wire resistance to earth at only 0.8Ω. Repair: Cut out the damaged loom section, resoldered the connections and applied double-layer heat-shrink tubing for insulation. Rerouted the loom to avoid contact with sharp edges. Cleared the fault codes and the SRS system passed its self-check. This case follows the same diagnostic approach as B2290 occupant classification system wiring faults.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin Pro B1670 side impact sensor connector water ingress and corrosion (reference case: similar connector fault B2692)

✓
Symptoms: A 2020 Qin Pro displayed an airbag warning light on the dashboard after driving through flood water, with DTC B1670 logged. Diagnosis: Inspected the side impact sensor located inside the right front door sill trim panel. The connector showed obvious water ingress and green copper corrosion, causing a short between the signal and earth pins. Root cause: the sunroof drain hose had perished and was leaking. Solution: Thoroughly cleaned the connector pins using electrical contact cleaner and fine sandpaper, sprayed conductive protectant, replaced the waterproof seal, and repaired the drain hose routing. Fault resolved. This case follows a similar troubleshooting procedure to B2692 seat belt buckle switch connector faults.
Original source ↗
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Tang DM B1670 Side Impact Sensor Internal Circuit Fault (Reference case: similar sensor body fault B00C8)

✓
Symptoms: A 2021 Tang DM airbag warning light came on intermittently during normal driving, especially over bumpy roads. VDS retrieved intermittent DTC B1670. Diagnosis: Initial inspection of the wiring harness and connectors found no issues. Measuring sensor harness resistance to earth showed an open circuit, within specification. After removing the sensor and testing the unit, intermittent continuity appeared between the internal signal terminal and the sensor housing (resistance fluctuated when shaking the sensor). This indicates a loose piezoelectric element or circuit board solder joint causing a short to the housing. Solution: Replaced the OEM right side impact sensor (part number matched to VIN). After installation, performed the SRS system configuration procedure. The fault did not reappear. This repair follows the same replacement procedure as B00C8 seat sensor internal faults.
Other Atto 8 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]