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 U

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 U indicates a high-severity short to battery power in the driver-side seat belt pretensioner second-stage firing circuit. This can disable the pretensioner and turn on the airbag warning light, reducing crash protection. Common causes include damaged wiring under the driver’s seat or B-pillar, or a corroded/deformed 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 — Seal U
  • 1Long-term chafing and wear of the wiring harness under the driver's seat or inside the B-pillar trim panel damages the pretensioner harness insulation, causing contact and a short circuit to the constant power supply wire (B+).
  • 2Water ingress, oxidation, or terminal deformation at the seat belt pretensioner connector (under the seat or on the B-pillar) causes a short circuit between the ignition circuit terminal and the power supply terminal.
  • 3Internal driver transistor breakdown in the SRS ECU or a control circuit fault causes the output terminal to continuously output high-level voltage.
  • 4Pretensioner body internal squib shorted to power, or squib resistance abnormally low (below 1.5 Ω).
  • 5During accident repairs, seat cover installation, or vehicle modifications, screws or brackets crush the wiring harness, or incorrect connections cause a short to power in 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 a safe system state.
  • 2
    Fault confirmation: Connect the diagnostic tool to read the fault codes. Confirm B1795-00 is active. Record the freeze frame data and check for other 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 fixing points near the seat slide rails.
  • 4
    Open circuit test: Disconnect the driver pretensioner connector. Use a multimeter to measure the voltage from both terminals on the harness side to body ground and the power supply; the normal value is 0V. Measure the resistance to ground; the normal value is infinite.
  • 5
    Pretensioner unit inspection: Measure the resistance between the two terminals of the pretensioner unit. The standard value is usually 2.0-3.0Ω (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 a multimeter on the high-resistance setting to measure the insulation resistance between the pretensioner drive circuit (SRS ECU to pretensioner) and the vehicle body power harness. The 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 using an oscilloscope 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 (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 U Fault Codes
B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173712DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
Common problems reported for Seal U →Seal U 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.