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B1795

DTC B1795 indicates a short to B+ in the driver-side seat belt pretensioner Stage 2 squib circuit — Atto 3

Safety System

DTC B1795 indicates a short to B+ in the driver-side seat belt pretensioner Stage 2 squib circuit.

In the BYD SRS system, the seat belt pretensioner uses a dual-stage ignition design: Stage 1 triggers early in a collision to provide basic tightening force, and Stage 2 triggers during a severe collision to generate greater tightening force to better restrain the occupant.

This DTC indicates the airbag control unit (ACU) detects an abnormal voltage increase in the Stage 2 pretensioner circuit to near battery voltage (12V) and an abnormal resistance value.

This fault prevents the pretensioner from deploying correctly during a collision because the short to power prevents the firing current from forming a complete circuit.

It may also damage the ignition driver chip inside the ACU.

Because this is an active safety system fault, the vehicle illuminates the airbag warning lamp and may fail to protect the driver properly during a collision.

5
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Seat adjuster chafed wiring harness causing short circuit

✓
2021 BYD Tang DM, 32,000 km. Airbag warning light on. Scanner read DTC B1795. Removing the driver's seat revealed the pre-tensioner harness bundled with the seat heater power wire underneath. Repeated seat adjustments wore through the harness sheath, shorting the pre-tensioner circuit to the heater constant live. Repair: Separated the harnesses, fixed the damage with double-layer heat shrink tubing, re-routed the wiring away from the seat rails, and added a protective sleeve. Fault resolved.
BYD DTC AI Analysis

Water ingress during car wash caused connector corrosion

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2019 BYD Yuan EV. Owner reported the airbag warning light illuminated after a car wash. Scan revealed DTC B1795. Inspection found the sealing ring on the pre-tensioner connector beneath the driver's seat had deteriorated. Water entered the connector during the wash, causing electrolytic corrosion between the terminals that created a short-circuit path. Replaced the connector housing and terminals, cleaned the wiring harness, applied waterproof silicone grease inside the connector, and rewrapped with waterproof tape. Fault has not returned.
BYD DTC AI Analysis

Internal short circuit in pretensioner assembly

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2020 Qin Pro (petrol). DTC B1795 appeared after accident repairs. The vehicle had sustained frontal impact damage; the front bumper and airbags were replaced, but the driver's seatbelt pretensioner was only reset, not replaced. Inspection revealed the pretensioner's internal secondary squib was damaged in the initial collision, breaking the insulation and causing a short to power. Replaced the OEM driver's seatbelt assembly (including pretensioner) to resolve the fault. Note: Replace pretensioners after deployment; never simply clear the fault codes.
BYD DTC AI Analysis

Aftermarket seat installation punctured the wiring harness.

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2019 Song MAX. Fault appeared after owner fitted leather seat upholstery and a ventilation system. Technicians found staples securing the seat cover had pierced the pretensioner harness and the seat ventilation motor power wire, causing a short. Replaced the damaged harness section. Pretensioner tested undamaged. Re-routed wiring to specification, avoiding staple locations.
BYD DTC AI Analysis

SRS control unit internal fault

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2021 Tang. Intermittent B1795, sometimes appearing on cold startup but disappearing when warm. Wiring harness and pretensioner tested normal. Suspected poor thermal stability of ACU internal secondary ignition drive circuit. Swapped ACU from normal vehicle for testing; fault transferred. Replaced airbag control unit and recoded to match. Fault eliminated.
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.