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) — Seal 6 EV

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 Seal 6 EV 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, reducing crash protection. Common causes include damaged wiring under the seat or B-pillar, or corroded/deformed pretensioner connector terminals. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from recorded cases.
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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1Long-term chafing of the wiring harness under the driver's seat or inside the B-pillar trim panel damages the insulation, shorting the pretensioner harness to the constant power supply wire (B+).
  • 2Water ingress, oxidation, or deformed terminals at the seat belt pretensioner connector (located under the seat or on the B-pillar), causing 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 voltage 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 pinching the wiring harness, or incorrect connections, feed power into 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 allow the SRS capacitor to fully discharge and ensure the system is in a safe state.
  • 2
    Fault confirmation: Connect the diagnostic tool and 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 (floor harness to B-pillar/seat connector section) for wear, crushing, water stains, or modifications. Focus on the harness mounting points near the seat slide rails.
  • 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: 0V. Measure the resistance to ground. Normal value: Infinite.
  • 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 model workshop manual). Replace the pretensioner assembly if the resistance is too low or if continuity exists between the terminals and the housing.
  • 6
    Harness insulation check: Use a megohmmeter or a multimeter set to the high-resistance range to measure the insulation resistance between the pretensioner drive circuit (SRS ECU to pretensioner) and the body power wiring harness. Resistance must be greater than 1MΩ. Otherwise, repair or replace the wiring 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, use an oscilloscope to monitor the ECU output waveform to check for an internal ECU short circuit. If necessary, replace the SRS ECU and perform coding configuration.
  • 8
    Repair verification: After repairing or replacing the faulty component, reconnect all connectors and the battery, clear the fault code, perform an SRS system self-check (turn ignition switch ON; indicator light should turn off), and 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 Seal 6 EV 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.B1737DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Seal 6 EV →Seal 6 EV 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.