AU
B1792

DTC B1792 indicates the driver-side second-stage seat belt pretensioner circuit resistance falls below the normal range calibrated by the SRS ECU (typically 2 — Qin Plus

Safety System

DTC B1792 indicates the driver-side second-stage seat belt pretensioner circuit resistance falls below the normal range calibrated by the SRS ECU (typically 2.0-3.0Ω).

The second-stage pretensioner features a seat belt retractor with a dual-stage igniter that deploys in stages based on collision severity.

A low resistance value (<1.5Ω or close to 0Ω) indicates abnormal conduction resulting from an internal short circuit in the pretensioner igniter, a wiring harness short to ground, or connector water ingress and oxidation.

This fault forces the SRS system into fail-safe mode, disabling the pretensioner and associated airbag functions.

In extreme cases, the pretensioner may deploy without a collision or fail to operate during a collision, severely compromising the occupant restraint system's protection performance.

The B1792 fault code on the Qin Plus indicates low resistance in the driver-side second-stage seat belt pretensioner circuit. Severity is medium because it can disable pretensioner and related airbag functions, reducing crash protection. Common causes include an internal short in the pretensioner igniter or water ingress, oxidation, or pin damage at the under-seat connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available from 4 recorded cases.
4
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Seat belt pretensioner internal igniter short circuit: Moisture ingress, aging, or manufacturing defects in the pretensioner cause the internal bridge wire to short to the housing, resulting in abnormally low resistance.
  • 2Wiring harness connector fault: Water ingress, oxidation, deformed pins, or loose connections at the K71 connector under the seat (pins 17/18) cause a signal wire short to ground or abnormal contact resistance.
  • 3Seat movement interference: Frequent seat adjustment causes the pretensioner wiring harness to chafe at the slide rail, wearing through the insulation and shorting the core wire to body ground.
  • 4SRS ECU detection circuit fault: Abnormal A/D conversion circuit or sampling resistor inside the airbag control module falsely reports low resistance (rule out via cross-validation).
  • 5Improper post-accident repair: failing to replace a deployed pretensioner after a collision, or incorrectly measuring with a multimeter on the high-current range during repair, causing a partial short circuit in the igniter.
What To Do
  • 1
    Safe power-down: Turn the power switch to OFF, disconnect the battery negative terminal, and wait at least 90 seconds to completely discharge the SRS capacitor and prevent accidental deployment.
  • 2
    Fault confirmation: Connect VDS or a dedicated diagnostic tool, read SRS system fault codes, confirm B1792 is a current fault and not a history fault, and record freeze frame data.
  • 3
    Visual inspection: Check the driver seat belt pretensioner for impact deformation or water stains. Check connector K71 for looseness and the pins for oxidation or deformation.
  • 4
    Resistance measurement: Disconnect connector K71. Use a high-precision multimeter to measure the pretensioner-side resistance (standard value: 2.0-3.0 Ω). If <1.5 Ω, replace the pretensioner assembly. Measure the harness-side resistance to ground (should be >1 MΩ). If abnormal, check the harness for a short circuit.
  • 5
    Harness continuity test: Measure continuity of KJ10-1 (Y/L wire) and KJ10-2 (B/Y wire) between the ECU and the pretensioner (should be <1Ω). Check insulation to body ground and power supply.
  • 6
    Replacement verification: If the pretensioner resistance is normal, install a known-good pretensioner for testing. If the fault code disappears, the original pretensioner has an internal fault.
  • 7
    Repair and verification: After repairing or replacing the faulty component, reconnect all connectors. Turn the power to ON and wait 20 seconds for the system self-check. Verify the fault code clears and the airbag warning light turns off. Perform a seat forward and backward movement test to confirm no intermittent faults.
Real-World Cases
BYD DTC AI Analysis

BYD Qin seatbelt pretensioner internal short circuit

✓
The instrument cluster airbag warning light stayed on. Retrieved DTC B1792-00. Disconnected the K71 connector and measured the driver's pretensioner resistance at only 0.8Ω (standard 2-3Ω), indicating an internal igniter short. Found water stains at the pretensioner mounting bracket from a previous sunroof leak; determined prolonged moisture exposure caused the internal short. Replaced the driver's seatbelt pretensioner assembly, cleared the sunroof drain blockage, and erased the fault codes. System returned to normal.
Original source ↗
BYD DTC AI Analysis

BYD Surui seat wiring harness poor contact

✓
Airbag warning light intermittent; DTC B1792 intermittent. Found the K71 connector under the driver's seat loose with visible pin oxidation. Measured pretensioner resistance—normal, but shaking the seat caused fluctuations and intermittent shorts. Frequent seat adjustments had dislodged the harness retaining clip, letting the seat rail interfere with the wiring. Cleaned the pin oxidation, applied conductive grease, re-secured the harness routing, and fitted anti-abrasion sleeving. Fault resolved.
BYD DTC AI Analysis

BYD G6 pretensioner fault after accident repair

✓
Front collision repairs left the SRS warning light on with stored codes B1792 and crash sensor fault. The driver's seatbelt pretensioner had deployed in the accident but was never replaced; the repairer only reset it. Resistance across the pretensioner measured infinite (open circuit), but the connector pins had deformed during repairs, shorting the signal wire to ground (false short). The ECU flagged the low resistance first. Replaced the pretensioner assembly, repaired the connector pins, and recalibrated the SRS ECU. Fault cleared.
BYD DTC AI Analysis

Water wading caused pretensioner short circuit in BYD Song MAX

✓
After 3 years, the airbag warning light suddenly lit up. No collision history. DTC B1792. Measured pretensioner resistance at 0.5Ω, significantly below spec. Found water ingress marks on the driver's side carpet and green corrosion inside the pretensioner connector. Traced the issue to a detached AC drain hose causing condensation buildup. Replaced the pretensioner assembly, cleaned the connector, repaired the AC drain hose, and dried and waterproofed the wiring harness. Fault resolved.
Other Qin Plus 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.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.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.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.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 Qin Plus →Qin Plus 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.