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B1641-00

DTC B1641-00 indicates an abnormal short to body ground in the driver-side seat belt pretensioner igniter circuit — Atto 3

Safety System

DTC B1641-00 indicates an abnormal short to body ground in the driver-side seat belt pretensioner igniter circuit.

In the BYD SRS (Supplemental Restraint System) architecture, a low-impedance igniter (normal resistance 2.1–3.0 Ω) triggers the pretensioner.

When the ECU detects circuit resistance below the threshold (typically <0.8 Ω), it determines a short to ground.

This fault causes the following: 1) The SRS system enters fail-safe mode, disabling the driver-side airbag and pretensioner functions; 2) The pretensioner may fail to deploy during a collision, causing occupant restraint failure; 3) Continuous short-circuit current risks unintended pretensioner deployment or SRS ECU driver circuit burnout.

This DTC is a hard fault requiring physical repair before clearing.

4
Cases Logged
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Worn seat rails in Qin EV300 causing intermittent short circuit

✓
A 2017 Qin EV300 with 80,000 km displayed an intermittent "Check SRS System" warning on the instrument cluster, with DTC B1641-00 logging intermittently. Inspection found the wiring harness protective sleeve behind the driver's seat rail had worn through on the rail's sharp edge, exposing bare copper cores. On bumpy roads, the damaged harness contacted the chassis, causing intermittent short-to-ground faults. Repair: wrapped the damaged area with insulating tape, fitted corrugated tubing for additional protection, and rerouted the harness to avoid the seat rail movement path. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin 80 pretensioner connector corroded after driving through water

✓
2017 BYD Qin 80. After wading through water approximately 40 cm deep, the airbag warning light remained on. Retrieved DTC B1641-00. Inspection revealed obvious water staining and green copper corrosion inside the driver pretensioner connector (yellow 2-pin plug) located below the B-pillar. Resistance between terminal and ground measured 0.3 Ω (short to ground). Cause: Connector seal deterioration led to seal failure when wading. Replaced the pretensioner wiring harness assembly (connector and harness as one unit). Removed corrosion from the ECU-side connector and applied electronic cleaner spray. Cleared fault codes; system returned to normal.
BYD DTC AI AnalysisFrom Chinese market (translated)

Replaced Qin EV450 pretensioner assembly due to internal short circuit

✓
2018 Qin EV450: Airbag warning light stays on continuously with DTC B1641-00 that cannot be cleared. Disconnected the pretensioner connector under the seat and measured infinite resistance to ground on the harness side (normal). Measured 0.2Ω between the pretensioner terminals and metal casing, confirming internal short to ground. Disassembled the seatbelt retractor and found moisture inside the pretensioner gas generator. Replaced the genuine driver's seatbelt assembly (part number: SA-5813100), performed SRS system configuration after installation, and resolved the fault.
BYD DTC AI AnalysisFrom Chinese market (translated)

Wiring harness clip not reset after seat removal and refitting, causing pinched short

✓
Case involves a 2017 BYD Qin 100. The customer reported that immediately after having the seat foam replaced at a repair shop, the airbag warning light illuminated upon starting the vehicle. Technicians found the pretensioner wiring harness trapped between the seat track mounting bolt and the chassis; damaged insulation caused a short to ground. Root cause: failure to reinstall the harness retaining clips during the seat repair allowed the harness to enter the seat slide rail travel path. Technicians replaced the damaged harness section, rerouted the harness per specification, secured the retaining clips, and checked full front-to-rear seat travel to confirm no interference.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
Data confidence: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.