AU
B1793

This DTC indicates the Airbag Control Module (ACM) detects the driver-side second-stage seatbelt pretensioner circuit resistance exceeds the calibrated range (typically 2-5 ohms) — Seal 6 EV

Safety System

This DTC indicates the Airbag Control Module (ACM) detects the driver-side second-stage seatbelt pretensioner circuit resistance exceeds the calibrated range (typically 2-5 ohms).

This Passive Safety System (SRS) circuit fault indicates high resistance or an open circuit in the pretensioner circuit.

The pretensioner is a critical protective device that uses a pyrotechnic charge to instantly tighten the seatbelt during a collision.

This fault indicates the driver-side seatbelt may fail to pretension correctly during a frontal collision, increasing occupant forward travel, reducing restraint system effectiveness, and posing a severe safety hazard.

The B1793 fault code on the Seal 6 EV indicates the Airbag Control Module has detected high resistance or an open circuit in the driver-side second-stage seatbelt pretensioner circuit. This is a medium-severity SRS fault that may reduce seatbelt protection in a crash. Common causes include a failing pretensioner coil or a loose, corroded, or wet under-seat connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
3
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1Open circuit, aging, or increased resistance in the internal coil of the driver seat belt pretensioner assembly.
  • 2Loose connection, backed-out terminal, oxidation, or water ingress at the under-seat pretensioner wiring harness connector (yellow plug) causing increased contact resistance.
  • 3Prolonged bending and wear of the pretensioner wiring harness at the seat slide rail causes internal wire breakage or a partial open circuit.
  • 4Water ingress or a high-humidity environment corrodes the pretensioner connector terminals, forming an oxide layer that increases resistance.
  • 5Airbag Control Module (ACM) internal sampling circuit fault or software calibration error (less common)
What To Do
  • 1
    Use the dedicated diagnostic tool to read the fault code, confirm whether B1793 is a current fault (Active) or a history fault (History), and record the resistance value from the freeze frame data.
  • 2
    Disconnect the 12V battery negative terminal and wait at least 90 seconds to fully discharge the airbag system capacitor (observe safety operating procedures).
  • 3
    Check the airbag wiring harness connector under the driver's seat (yellow-marked plug) for looseness, backed-out pins, oxidation, or signs of water ingress. Clean the terminals with electrical contact cleaner, apply conductive grease, and reconnect.
  • 4
    Remove the driver seat. Inspect the pretensioner wiring harness insulation for wear at the seat slide rail bend. Measure the wiring harness continuity and resistance between the connector and the pretensioner.
  • 5
    Disconnect the pretensioner connector and use a multimeter to measure the resistance of the pretensioner unit (normal range: 2-5 Ω). If the resistance is infinite or >5 Ω, the pretensioner unit is faulty. Replace the driver seat belt pretensioner assembly.
  • 6
    Measure wiring harness continuity between the pretensioner connector and the Airbag Control Module (ACM), focusing on the floor harness junction. Repair high-resistance or open circuits. Replace the wiring harness if necessary.
  • 7
    Reinstall the seat and all connectors. Ensure the wiring harness does not interfere with the seat slide rails throughout their full travel. Connect the battery, clear the fault code, and perform a system self-check (turn the ignition switch to the ON position and verify the SRS warning lamp turns off normally).
  • 8
    Perform a road test or simulate seat forward and backward movement and jolting vibrations to confirm the fault code does not recur and the system returns to normal operation.
Real-World Cases
BYD DTC AI Analysis

BYD Song MAX: Loose connection in wiring harness under seat caused SRS fault.

✓
Symptoms: Airbag warning light stays illuminated. Scanned and retrieved restraint system fault codes. Vehicle has no collision history; warning light remains on. Diagnosis: Checked wiring harness connector under driver's seat. Found loose connection with oxidized pins; measured contact resistance >10Ω. Inspected wiring at seat rails; no mechanical damage. Repair: Cleaned and re-secured seat harness connector, sanded terminals to remove oxidation, applied conductive grease to prevent further oxidation, cleared fault codes. Warning light extinguished; system returned to normal.
BYD DTC AI Analysis

BYD F3 Seat Belt Buckle Switch Circuit Fault (similar to B2692 case)

✓
Symptoms: Airbag warning light illuminates intermittently after startup with beeping alarm. No obvious correlation with driver seatbelt use; occurs occasionally on rough roads. Diagnosis: Scan tool retrieved seatbelt buckle switch circuit fault from airbag system. Wiring harness beneath driver seatbelt buckle showed internal conductor breakage from long-term flexing. Seatbelt buckle switch had intermittent contact. Resolution: Replaced driver seatbelt buckle assembly (with switch), repaired broken harness and added protective sleeve. Cleared codes with scan tool; road test confirmed warning light and alarm no longer occur.
Original source ↗
BYD DTC AI Analysis

BYD Tang: Water ingress in seat belt pretensioner connector caused corrosion and high resistance.

✓
Symptoms: Airbag warning light stayed on after driving through water. Scan tool retrieved DTC B1793 for high resistance in the driver's second-stage seatbelt pretensioner. Diagnosis: Removed the driver's seat and found the pretensioner connector (yellow waterproof plug) had water staining and green copper corrosion inside. The pretensioner body measured 3.2Ω (normal), but resistance through the harness read infinite with the connector attached. Corroded terminals were causing an open circuit. Repair: Replaced the connector terminals, dried and resealed the plug, applied conductive grease, and reconnected. Cleared the codes and the system returned to normal. Recommendation: Inspect the floor sealing strips to prevent water ingress.
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.