AU
B1797-00

This DTC indicates the front passenger seat belt pretensioner (second-stage deployment circuit) resistance is 0 Ω, indicating a short circuit — Seal 6 EV

Safety System

This DTC indicates the front passenger seat belt pretensioner (second-stage deployment circuit) resistance is 0 Ω, indicating a short circuit.

In the BYD SRS (Supplemental Restraint System) architecture, the dual-stage pretensioner deploys in stages based on collision severity: the first stage provides light tightening, and the second stage provides strong tightening to secure the occupant.

A 0 Ω resistance usually indicates an internal short circuit in the pretensioner generator winding, a wiring harness short to ground, or a short between connector terminals.

Upon detecting this fault, the SRS ECU enters fail-safe mode and disables the pretensioner circuit.

This may cause the second-stage protection to fail during a collision or create a risk of unintended deployment; therefore, the system illuminates the airbag warning lamp.

The B1797-00 fault code on the Seal 6 EV indicates a medium-severity short circuit in the front passenger seat belt pretensioner second-stage deployment circuit. Common causes include an internal short in the pretensioner generator or chafed seat wiring shorting against the seat frame or track. The airbag warning light may come on, and the pretensioner may be disabled. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Seal 6 EV
  • 1Pretensioner generator internal short circuit: A broken bridge wire inside the pyrotechnic generator or a damp charge causes the resistance between the two terminals to drop to 0.
  • 2Seat wiring harness chafed and shorted: Prolonged friction between the pretensioner wiring harness and the seat track or frame during front passenger seat forward and backward adjustment damages the insulation, causing a short to ground.
  • 3Connector water ingress and corrosion: Water enters the pretensioner connector (usually located under the seat) during vehicle wading or interior cleaning, causing a short circuit between terminals.
  • 4Improper modification or repair: Fixing screws piercing the wiring harness or incorrect terminal crimping when installing seat covers or modifying seat heating or power adjustment.
  • 5SRS ECU internal fault: Damaged internal sampling resistor or detection circuit causes a false 0 ohm reading (actual circuit is normal).
What To Do
  • 1
    Safety preparation: Disconnect the 12V battery negative terminal and wait at least 90 seconds to fully discharge the SRS capacitor and prevent accidental airbag deployment.
  • 2
    Visual inspection: Remove the front passenger seat (leave the wiring harness connected) and inspect the pretensioner connector under the seat (usually yellow) for looseness, water ingress, or obvious burn marks.
  • 3
    Disconnect and measure at the ECU side: Locate the SRS ECU (usually under the centre console or behind the armrest). Disconnect the front passenger pretensioner connector. Measure the resistance to earth on the wiring harness side. Resistance must be greater than 10kΩ; otherwise, the wiring harness has a short to earth.
  • 4
    Pretensioner unit measurement: Disconnect the inflator connector. Use a dedicated low-impedance multimeter to measure the resistance between the two terminals of the pretensioner connector. Normal resistance is 2.0-5.0Ω. If the resistance is 0Ω, replace the pretensioner assembly.
  • 5
    Harness continuity check: If Step 3 reveals a short circuit, inspect along the seat harness sleeve to the floor harness, focusing on seat slide rail interference points. Repair damaged insulation and reroute the harness.
  • 6
    Replacement verification: After replacing the suspected faulty pretensioner or repairing the wiring harness, reconnect all components and the battery, clear the fault code using the diagnostic tool, and perform an 'ignition cycle test' and 'pretensioner resistance reading' to verify the repair.
  • 7
    System simulation test: On some models, perform SRS system self-learning or write configuration data so the ECU recognizes the new component parameters.
Real-World Cases
BYD DTC AI Analysis

Worn seat rails shorted the wiring harness

✓
Vehicle: Qin EV300 2018. Customer reported the airbag warning light on. Scan tool retrieved DTC B1797-00. Inspection found the passenger seat base harness chafed against the metal bracket when the seat was in the full forward position, wearing through the insulation and causing a short to ground. Repaired the damaged harness (3 wires, including 1 pretensioner signal wire), re-secured the harness routing, added corrugated tubing protection, and repositioned the cable clips to avoid contact with moving parts. Fault resolved.
BYD DTC AI Analysis

Connector corrosion and short circuit after water ingress

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Vehicle: Qin 100 2017. After driving through water, the passenger carpet was wet and the airbag light came on. Disassembly revealed water in the pretensioner connector under the passenger seat. Copper terminals had oxidized, producing green corrosion that shorted adjacent terminals. Repair: Cleaned the connector terminals with electronic cleaner and a specialty brush, dried the wiring harness, applied conductive grease, and replaced the connector seal. Pretensioner resistance measured normal at 2.3Ω. Cleared fault codes; no recurrence.
BYD DTC AI Analysis

Pretensioner generator internal short circuit

✓
Vehicle: Qin EV450 2018. Replaced the passenger side seat belt assembly after collision repairs. Post-installation DTC B1797-00 set. Measured the new seat belt pretensioner resistance at 0.2Ω (near short). Disassembling the old part revealed the new unit was aftermarket with an internal bridge wire design defect. Solution: Installed a genuine passenger side seat belt assembly (including pretensioner). Resistance: 2.8Ω. Fault code cleared after installation; SRS self-diagnostic passed.
BYD DTC AI Analysis

Aftermarket seat heater installation caused short circuit

✓
Model: Qin 80 2017. One week after the customer installed an aftermarket passenger seat heating pad, the airbag warning light came on. Inspection found incorrect splicing during the power tap; damaged insulation on the heating pad power wire had shorted to the pretensioner harness. Fix: Removed the unauthorized modification, restored the factory harness insulation with heat-shrink tubing, and remeasured pretensioner circuit resistance and insulation to ground. Advised the customer that SRS system wiring prohibits unauthorized modification.
BYD DTC AI Analysis

SRS ECU detection circuit false positive

✓
Model: Qin EV300 2017. Measured pretensioner and harness resistance multiple times; readings were normal (2.5Ω, good insulation to ground), but the DTC kept returning. Diagnosis: SRS ECU internal sampling circuit fault causing false 0Ω detection. Fix: Replaced the SRS control unit (programmed to match vehicle VIN and configuration codes). After replacement, the DTC has not returned and system function is normal.
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.