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 8

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 8 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 driver’s seat or B-pillar, or water-damaged/oxidised 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 — Atto 8
  • 1Long-term chafing of the wiring harness under the driver's seat or inside the B-pillar trim damages the insulation, shorting the pretensioner harness to the constant power wire (B+).
  • 2Water ingress, oxidation, or deformed terminals in the seat belt pretensioner connector (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 supply, or squib resistance abnormally low (below 1.5Ω).
  • 5During accident repairs, seat cover installation, or vehicle modifications, screws or brackets pinch the wiring harness, or incorrect connections cause power to enter the pretensioner circuit.
What To Do
  • 1
    Safety preparation: Disconnect the 12V 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 other associated 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 harness-side terminals to body ground and the power supply. Normal value: 0 V. Measure the resistance to ground. Normal value: Infinite.
  • 5
    Pretensioner unit inspection: Measure the resistance between the two pretensioner unit terminals. 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 the high-resistance range of a multimeter to measure the insulation resistance between the pretensioner drive circuit (SRS ECU to pretensioner) and the 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 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. Perform the SRS system self-check (ignition switch ON; indicator lamp should turn off) and simulate a crash test (use the special 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 8 Fault Codes
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.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.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.