AU
B1797-00

This DTC indicates the front passenger seat belt pretensioner (second-stage deployment circuit) resistance is 0 Ω, indicating a short circuit — Atto 8

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 Atto 8 indicates a short circuit in the front passenger seat belt pretensioner second-stage deployment circuit, with resistance reading 0 Ω. Severity is medium because the SRS may disable this pretensioner stage and turn on the airbag warning lamp. Common causes include an internal pretensioner generator short or damaged seat wiring near the rail or frame. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
5
Cases Logged
5
Causes
Likely Causes — Atto 8
  • 1Pretensioner generator internal short circuit: The internal bridge wire of the pyrotechnic generator breaks or the charge absorbs moisture, causing the resistance between the two terminals to drop to 0.
  • 2Seat wiring harness wear and short circuit: Prolonged friction between the pretensioner wiring harness and the seat rail or frame during front passenger seat fore/aft adjustment damages the insulation and causes a short to ground.
  • 3Connector water ingress and corrosion: Water entering the pretensioner connector (usually located under the seat) during vehicle wading or interior cleaning causes 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 the seat heating or power adjustment system.
  • 5SRS ECU internal fault: Damaged ECU 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). Inspect the pretensioner connector under the seat (usually yellow) for looseness, water ingress, or obvious burn marks.
  • 3
    Disconnect the ECU side and measure: Locate the SRS ECU (usually under the center console or behind the armrest). Disconnect the front passenger pretensioner connector and measure the resistance to ground on the wiring harness side. The resistance must be greater than 10kΩ. Otherwise, the wiring harness has a short to ground.
  • 4
    Pretensioner unit measurement: Disconnect the inflator connector. Use a special low-impedance multimeter to measure the resistance between the two terminals of the pretensioner plug. Standard resistance is 2.0-5.0 Ω. If the resistance is 0 Ω, 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 interference points at the seat slide rail. Repair any 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. Use the diagnostic tool to clear the fault code, then perform an 'ignition cycle test' and 'pretensioner resistance value reading' to verify.
  • 7
    System simulation test: Some models require SRS system self-learning or configuration writing for the ECU to recognize 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

✓
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 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.