UAE
AU
B179E00

This fault code indicates the Airbag Control Unit (ACU) detects an abnormal electrical series connection between an airbag ignition circuit (e — Atto 3

Safety System

This fault code indicates the Airbag Control Unit (ACU) detects an abnormal electrical series connection between an airbag ignition circuit (e.g., driver/front passenger frontal airbag, side airbag, or curtain airbag) and another vehicle electrical circuit (e.g., another airbag circuit, seat belt pretensioner circuit, or sensor circuit).

Normally, each ignition circuit remains independent with a specific resistance (typically 2.0 ± 0.2 Ω).

When a series connection occurs, total circuit resistance increases abnormally (combining to exceed 4 Ω) or the control unit detects cross-circuit signal interference.

This prompts the ACU to flag compromised circuit integrity.

This fault can prevent airbag deployment during a collision (due to insufficient ignition energy) or cause unintended deployment, severely compromising occupant protection.

3
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Seat wiring harness series fault in water-damaged vehicle

✓
A 2019 Qin PRO DM drove through floodwater after heavy rain in Guangdong, and the dashboard displayed 'Check SRS System'. The scan tool retrieved codes B179E00 and B179D00 (passenger airbag circuit malfunction). Disassembly revealed water in the wiring harness connectors beneath the front seats; green corrosion between the terminals had connected the driver side airbag circuit in series with the passenger side pretensioner circuit. Technicians thoroughly cleaned the seat wiring harness connectors, replaced the waterproof seals, blew out the harness interior with compressed air, confirmed normal insulation resistance, then cleared the fault codes. Check wiring harness sealing at other low-lying areas of the vehicle.
BYD DTC AI Analysis

Accident repair misconnected wiring harness, causing series connection

✓
A 2018 Qin PRO petrol sustained front-end impact damage. An independent workshop replaced the driver's airbag, clock spring and seatbelt pretensioners. After the repair, the airbag warning light stayed on. Scanning revealed DTC B179E00. Inspection showed the workshop had swapped the driver's seat pretensioner connector with the side airbag connector when reconnecting the yellow plugs beneath the seat. Both connectors share identical specifications but different pin definitions, causing ignition circuit 1 and ignition circuit 2 to connect in series. Repositioned the connectors according to the service manual wiring diagram (section SRS-10) and verified that each airbag component's 2-pin plug matched the corresponding colour markings on the harness. Fault resolved.
BYD DTC AI Analysis

Clock spring internal break caused series circuit

✓
A 2019 Qin PRO DM's airbag warning light illuminated suddenly while driving; no collision history. Diagnosis revealed DTC B179E00 accompanied by B176200 (driver airbag short-to-ground history code). Steering wheel removal revealed a fractured flat cable inside the clock spring (spiral cable). The broken wire intermittently contacted other metal components during steering rotation, creating an intermittent series connection between the driver-side stage 1 and stage 2 airbag circuits. Replaced the clock spring with a genuine part (part number HA2E-5820000), calibrated the steering wheel angle sensor, and performed the 'airbag system configuration' procedure using a diagnostic tool to ensure resistance matching of the new component.
Other Atto 3 Fault Codes
P0A0DBattery Energy Control Module Requested MIL IlluminationP0AA6Hybrid Battery Voltage System Isolation FaultP1A00Drive Motor "A" Performance — BYD proprietaryB1108For 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.
Data confidence: Community This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.