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B179F00

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

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.

The B179F00 fault code on the Qin Plus indicates a problem in the SRS airbag sensor series circuit. Severity is medium, but it is safety-critical because it can put the airbag system into degraded mode and may affect deployment. Common causes include damaged crash sensor wiring in the bumper or B-pillar, or water ingress and corrosion at the under-seat occupancy sensor connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Wear, open circuit, or poor connection in the front bumper or B-pillar crash sensor wiring harness due to chassis scraping or improper accident repairs.
  • 2Improper cleaning or liquid spills lead to water ingress and pin oxidation at the under-seat occupancy sensor connector, causing abnormal circuit resistance.
  • 3Failing to tighten the sensor or wiring harness to the specified torque after accident repairs causes poor grounding or damages the shielding layer, resulting in signal interference.
  • 4SRS ECU internal detection circuit fault or abnormal software calibration causes misjudgment of normal circuit resistance.
  • 5Unauthorized modifications (such as installing seat covers or non-OEM seats) damage the integrity of the sensor series circuit.
What To Do
  • 1
    Use the BYD VDS2000/VDS2100 diagnostic tool to read 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 fully discharge. Check the airbag warning light status on the instrument cluster.
  • 3
    Visually inspect the front collision sensors (located on both sides of the radiator support) and the side collision 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 pins, or spread terminals.
  • 5
    Use a multimeter to measure the total resistance of the sensor series circuit (the standard value is typically the sum of the series sensor resistances; each sensor is approximately 2-3 kΩ). Infinite resistance indicates an open circuit; resistance near 0 Ω indicates a short circuit.
  • 6
    Perform sectional measurement: disconnect intermediate connectors (e.g., G09, G10) and measure wiring harness continuity between the sensor and the ECU section by section to locate the open or short circuit.
  • 7
    If the wiring harness is normal, replace the suspected sensors one by one (replace the seat occupancy sensor first due to its higher historical failure rate). After each replacement, clear the fault code and perform a system self-diagnosis.
  • 8
    After repair, reconnect all components and restore battery power. 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 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.