AU
B1795-00

DTC B1795-00 indicates the airbag control module (SRS ECU) detects an abnormal short to vehicle power (B+) in the driver-side seat belt pretensioner drive circuit (second-stage firing circuit) — Atto 3

Safety System

DTC B1795-00 indicates the airbag control module (SRS ECU) detects an abnormal short to vehicle power (B+) in the driver-side seat belt pretensioner drive circuit (second-stage firing circuit).

In a dual-stage pretensioner system, the second stage further tightens the seat belt during a severe collision.

Normally, this circuit remains open or low.

When the ECU detects the pretensioner circuit voltage continuously exceeding the threshold (near the 12V battery voltage), it registers a short to power.

This fault causes the ECU to immediately disable the pretensioner circuit and illuminate the airbag warning light.

In extreme cases, the pretensioner may fail to deploy or deploy abnormally during a collision.

This severe fault compromises occupant safety.

The B1795-00 fault code on the Atto 3 indicates a high-severity short to battery power in the driver-side seat belt pretensioner second-stage circuit. This can disable the pretensioner and turn on the airbag warning light, affecting crash protection. Common causes include damaged wiring under the seat or B-pillar, or corrosion/deformed terminals at the pretensioner connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Atto 3
  • 1Prolonged chafing of the wiring harness under the driver's seat or inside the B-pillar trim panel damages the insulation, causing the pretensioner harness to contact and short circuit to the constant power supply wire (B+).
  • 2Water ingress, oxidation, or terminal deformation at the seat belt pretensioner connector (located under the seat or on the B-pillar) causes a short circuit between the ignition circuit terminal and the power supply terminal.
  • 3SRS ECU internal drive transistor breakdown or control circuit fault causes continuous high-level power at the output terminal.
  • 4Pretensioner internal squib shorted to power, or squib resistance abnormally low (below 1.5 Ω)
  • 5During vehicle accident repairs, seat cover installation, or modifications, screws or brackets crush the wiring harness, or incorrect connections short power to the pretensioner circuit.
What To Do
  • 1
    Safety preparation: Disconnect the battery negative terminal and wait at least 3 minutes (or the time specified in the repair manual) to fully discharge the SRS capacitor and ensure the system is in a safe state.
  • 2
    Fault confirmation: Connect the diagnostic tool to read fault codes. Confirm B1795-00 is active. Record freeze frame data and check for accompanying SRS fault codes.
  • 3
    Visual inspection: Remove the driver-side B-pillar lower trim panel and seat. Inspect the pretensioner wiring harness (section from the floor harness to the B-pillar/seat connector) for wear, crushing, water stains, or signs of modification. Focus on the harness mounting points near the seat slide rail.
  • 4
    Open circuit test: Disconnect the driver pretensioner connector. Use a multimeter to measure the voltage from both harness-side terminals to body ground and power supply; normal value is 0V. Measure the resistance to ground; normal value is infinity.
  • 5
    Pretensioner unit inspection: Measure the resistance between the two terminals of the pretensioner unit. The standard value is usually 2.0-3.0 Ω (refer to the specific vehicle workshop manual). If the resistance is too low or continuity exists between the terminals and the housing, replace the pretensioner assembly.
  • 6
    Harness insulation check: Use a megohmmeter or multimeter high-resistance setting to measure the insulation resistance between the pretensioner drive circuit (SRS ECU to pretensioner) and the body power harness. Resistance must be greater than 1MΩ. Otherwise, repair or replace the harness.
  • 7
    ECU diagnosis: If the wiring harness and pretensioner are normal, check the SRS ECU connector terminals for corrosion or backed-out pins. If necessary, monitor the ECU output waveform with an oscilloscope to check for an internal ECU short circuit. Replace the SRS ECU and perform coding configuration if necessary.
  • 8
    Repair verification: After repairing or replacing the faulty component, reconnect all connectors and the battery. Clear the fault code and perform an SRS system self-check (ignition switch ON; the indicator lamp should turn off). Simulate a crash test (use a dedicated test resistor in place of the pretensioner) to confirm normal system operation.
Real-World Cases
BYD DTC AI Analysis

BYD Qin EV300 seat track wiring harness chafed and shorted

✓
Airbag warning light stayed on. Diagnostic scan retrieved DTC B1795-00 (Driver Second Stage Seatbelt Pretensioner Short to Power). Inspection found the wiring harness under the driver's seat had chafed against the fore-aft adjustment rails over time, damaging the insulation and causing the pretensioner power wire to short to constant B+. Repaired the damaged wiring, rerouted the harness away from moving components, and secured it with dedicated cable clips. Cleared the fault codes; system returned to normal.
Original source ↗
BYD DTC AI Analysis

After accident repairs on the Qin 80, misaligned connector terminals caused a short circuit.

✓
A Qin 80 had its driver seat belt assembly replaced at a non-authorised repairer after a collision. The airbag warning light came on the day after delivery. Techs retrieved DTC B1795-00. Inspection found the pretensioner connector terminals installed incorrectly, causing the second-stage ignition circuit terminal to short against the power terminal. Reinstalling the terminals correctly and confirming the lock tabs engaged cleared the fault.
BYD DTC AI Analysis

BYD Qin EV450 – Water ingress into floor wiring harness after wading

✓
After driving through water, water entered the driver's side carpet and the airbag warning light stayed on with DTC B1795-00 stored. Inspection revealed the floor harness connector seal under the driver's seat had failed. Water ingress caused electrolytic oxidation between the terminals, dropping the insulation resistance between the pretensioner drive circuit and power supply circuit to 0.5Ω. Thoroughly cleaned and dried the connector, applied conductive protectant, and replaced the seal to clear the fault.
BYD DTC AI Analysis

Qin Pro SRS ECU internal driver circuit fault

✓
No accident history. Airbag warning light suddenly illuminated while driving. DTC B1795-00. Checked pretensioner wiring harness insulation and connectors—good. Pretensioner resistance measured 2.3Ω (normal). Disconnected pretensioner; ECU-side output terminals still outputting constant 12V. SRS ECU internal drive transistor shorted. Replaced SRS control unit, performed VIN coding and system configuration. Fault resolved.
Other Atto 3 Fault Codes
P0AA6Hybrid Battery Voltage System Isolation FaultB1108For 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.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.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.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.
Common problems reported for Atto 3 →Atto 3 overview →
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.