NO
AU
B1772-00

DTC B1772-00 indicates the airbag control unit (SRS ECU) detects the right rear seatbelt pretensioner circuit resistance exceeds the calibrated range (normal range: 1 — Atto 3

Safety System

DTC B1772-00 indicates the airbag control unit (SRS ECU) detects the right rear seatbelt pretensioner circuit resistance exceeds the calibrated range (normal range: 1.8–3.0Ω; high resistance typically indicates >5Ω or infinite).

As a key passive safety system actuator, the pretensioner features a pyrotechnic design, using propellant gas to instantly tighten the seatbelt during a collision.

High resistance indicates a high-impedance connection or open circuit.

Causes include poor connector contact, a damaged wiring harness, or an open gas generator coil inside the pretensioner.

This fault continuously illuminates the SRS warning light and can trigger a degraded system mode.

During a collision, the pretensioner may fail to deploy, and the SRS ECU may suspend the right rear side airbag deployment logic, significantly reducing crash protection for the right rear passenger.

3
Cases Logged
Real-World Cases
BYD DTC AI Analysis

BYD Song Pro DM-i: Seat wiring harness poor contact

✓
Symptoms: SRS warning light stays on. Scan tool shows DTC B1772-00 (Driver seat occupancy status uncertain). Returns after clearing. Diagnosis: Found the Occupant Detection System (ODS) connector (left side of seat rail) had a broken locking tab causing poor contact. Resistance fluctuated between open circuit and 800 Ω (normal: 380–420 Ω). Solution: Replaced the wiring harness connector, re-crimped terminals and secured the harness. Performed Seat Calibration. Fault cleared.
BYD DTC AI Analysis

BYD Qin Plus EV seat pressure sensor internal leak

✓
Symptoms: Airbag warning light occasionally flickers when driving on rough roads; stored DTCs B1772-00 and B1650-00. Diagnosis: Live data showed the Occupant Detection signal jumping erratically between 0% and 100%. Removed the seat and found the pressure-sensing bladder (Bladder) cracked at the edge with internal silicone medium leaking; output voltage dropped to 0.8V (normal 2.5V). Resolution: Replaced the driver's seat cushion assembly (including occupant sensor) and performed the seat calibration procedure to learn the pressure baseline.
BYD DTC AI Analysis

BYD Tang DM wiring harness damaged after accident repair

✓
Symptom: After left front collision repairs, the airbag warning light stays on constantly and DTC B1772-00 will not clear. Diagnosis: During accident repair, seat removal pinched the yellow SRS harness against the seat rails. Damaged insulation caused an intermittent short between the signal wire and ground. Repair: Cut out the damaged section and spliced in high-temperature flame-retardant flying leads. Insulated with double-layer heat-shrink tubing. Rerouted the harness with 20cm slack. Cleared the fault codes; self-test passed.
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.