AU
B179F00

DTC B179F00 indicates a fault in the sensor series circuit of the SRS (Supplemental Restraint System/airbag system) — Seal 6 EV

Safety System

DTC B179F00 indicates a fault in the sensor series circuit of the SRS (Supplemental Restraint System/airbag system).

In the BYD Qin PRO, a series or parallel circuit typically connects multiple safety sensors (including the front impact sensor, side impact sensor, and seat occupancy sensor) to the SRS ECU.

The ECU determines sensor status by monitoring the circuit resistance and voltage signals.

The ECU triggers this DTC when it detects abnormal circuit resistance (open circuit, short circuit, or resistance outside the calibrated range of 2.0-4.5kΩ), an incorrect signal sequence, or a communication interruption.

This fault forces the airbag system into a degraded mode.

In extreme cases, it prevents normal airbag deployment during a collision or creates a risk of unintended deployment.

This is a safety-critical fault.

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Cases Logged
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Causes
Likely Causes — Seal 6 EV
  • 1Wear, open circuit, or poor connection in the front bumper or B-pillar collision sensor wiring harness due to chassis scraping or improper accident repairs.
  • 2Improper cleaning or liquid spills cause water ingress and pin oxidation at the under-seat occupancy sensor connector, resulting in abnormal circuit resistance.
  • 3Failure to install the sensor or wiring harness to the specified torque after accident repairs causes poor grounding or shielding layer damage, resulting in signal interference.
  • 4SRS ECU internal detection circuit fault or abnormal software calibration, causing misjudgment of normal circuit resistance.
  • 5Improper modifications (such as installing seat covers or replacing with non-OEM seats) compromised the integrity of the sensor series circuit.
What To Do
  • 1
    Use the BYD VDS2000/VDS2100 diagnostic tool to read the complete fault codes and freeze frame data. Record the vehicle status at the time of the fault and check for accompanying fault codes (e.g., B179E00, B17A000).
  • 2
    Disconnect the battery negative terminal and wait at least 90 seconds for the SRS capacitor to discharge completely. Check the instrument cluster airbag warning light status.
  • 3
    Visually inspect the front impact sensors (located on both sides of the radiator support) and the side impact sensors (located behind the B-pillar trim panels) for signs of impact or wiring harness damage.
  • 4
    Remove the seat and inspect the seat occupancy sensor (pressure sensor) GJ* series connector (depending on specific vehicle configuration) for green oxidation, backed-out terminals, or spread pins.
  • 5
    Use a multimeter to measure the total resistance of the sensor series circuit (the standard value usually equals the sum of the series sensor resistances; each sensor is approximately 2-3kΩ). Infinite resistance indicates an open circuit; resistance near 0Ω indicates a short circuit.
  • 6
    Use the sectional measurement method: disconnect intermediate connectors (e.g., G09, G10) and measure wiring harness continuity between the sensor and ECU section by section to locate the open or short circuit.
  • 7
    If the wiring harness is normal, replace the suspect sensors one by one (start with the seat occupancy sensor due to its higher historical failure rate). After each replacement, clear the fault code and perform a system self-diagnosis.
  • 8
    After completing the repair, reconnect all components and the battery. Use the diagnostic tool to perform 'SRS system configuration' and 'sensor calibration' (if applicable). Finally, perform a simulated crash signal test (use a dedicated resistor; do not short-circuit directly).
Real-World Cases
BYD DTC AI Analysis

Qin Pro DM front impact sensor wiring harness chafed, causing intermittent open circuit

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Vehicle: 2018 BYD Qin PRO DM, 68,000 km. Symptoms: Dashboard airbag warning light illuminates intermittently, with increased frequency on rough roads. VDS scan retrieved DTCs B179F00 (sensor series circuit fault) and B162000 (left front collision sensor fault). Diagnosis: Lifted the vehicle and found the left front collision sensor harness had chafed against the sheet metal edge where it passes through the wheel arch liner. Long-term vibration wore through the insulation and partially severed the copper wires, leaving them intermittently connected. The series circuit resistance read normal at rest but opened intermittently under vibration. Repair: Repaired the damaged harness, protected it with corrugated tubing and rerouted it away from the sharp sheet metal edges. Fault cleared.
BYD DTC AI Analysis

Water ingress caused oxidation in the seat occupancy sensor connector, resulting in circuit resistance drift.

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Vehicle: 2019 Qin PRO petrol, 42,000 km. Symptoms: SRS warning light constantly on, DTC B179F00; no collision. Diagnosis: Water stains on the seat base. Owner reported a blocked sunroof drain recently let water into the cabin. Removed the driver's seat and found green corrosion on the occupancy sensor pins (GJ301 connector). The corrosion dropped total resistance in the sensor series circuit from the normal 6.8 kΩ to 2.1 kΩ, below the ECU threshold. Repair: Cleaned the connector with electrical contact cleaner, dried the assembly, replaced damaged harness terminals, and cleared the sunroof drain. Fault resolved.
BYD DTC AI Analysis

After accident repairs, poor grounding of the B-pillar side impact sensor caused signal interference.

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Vehicle: 2018 Qin Pro DM, accident-repaired. Symptom: Right B-pillar impact. After 4S dealership repairs, SRS warning light stayed on and DTC B179F00 would not clear. Diagnosis: Right front seat side impact sensor (GJ302) mounting bolt was not tightened to the 9 N·m spec, causing poor ground between the sensor housing and body. This created noise voltage in the series circuit. Oscilloscope check found abnormal pulse interference on the sensor signal line. Resolution: Sanded the ground point clean to remove paint and oxidation; reinstalled the sensor at 9 N·m with conductive paste; ran SRS system configuration. Fault cleared.
BYD DTC AI Analysis

Aftermarket seat modification caused series circuit interruption

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Vehicle: 2019 Qin Pro petrol variant. Symptom: SRS warning light illuminated the day after the owner fitted aftermarket sport seats. Diagnostic procedure: Retrieved DTC B179F00. Inspection found that during the seat modification, the workshop did not transfer the original seat occupancy sensor to the new seats and simply wrapped the harness terminals with insulating tape. This created an open circuit in the series loop at the seat position. Repair: Installed the OEM occupancy sensor into the new seat cushion (required professional cutting and securing), restored the harness connections, cleared the DTCs with a diagnostic tool, and performed Occupant Classification System Calibration. System returned to 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.