UAE
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B174C

DTC B174C indicates the SRS (Supplemental Restraint System) detects the inflator resistance of the left rear side airbag (usually located inside the left rear C-pillar trim panel or on the side of the left rear seat) exceeds the system-calibrated threshold (typically above 3 — Atto 3

Safety System

DTC B174C indicates the SRS (Supplemental Restraint System) detects the inflator resistance of the left rear side airbag (usually located inside the left rear C-pillar trim panel or on the side of the left rear seat) exceeds the system-calibrated threshold (typically above 3.0Ω; normal range is 1.5Ω-3.0Ω).

This fault indicates a high-resistance condition or open circuit in the airbag inflator circuit.

Inflator aging, poor wiring harness contact, or a broken wire can cause this condition.

This fault prevents the airbag from deploying correctly during a side-impact collision and continuously illuminates the dashboard airbag warning light (SRS light).

The system enters fail-safe mode, and some models may limit the seat belt pretensioner function.

3
Cases Logged
Real-World Cases
BYD DTC AI Analysis

Worn left rear C-pillar wiring harness caused B174C fault in BYD Tang DM

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The SRS warning light on the instrument panel stayed on. Scan tool showed active fault code B174C. Removed the left rear C-pillar trim and found the side airbag wiring harness rubbing against the edge of the C-pillar sheet metal hole. The insulation wore through, 90% of the copper strands broke, and only a few strands remained connected, causing intermittent resistance readings. Repair: Cut out the damaged section. Soldered in new 0.5mm² high-temperature fluoroplastic wire (overlap ≥20mm). Insulated with double-layer heat-shrink tubing. Rerouted the harness away from sharp sheet metal edges. Fault cleared.
Original source ↗
BYD DTC AI Analysis

BYD Song Pro Left Rear Side Airbag Connector Oxidation Case

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After three years of use, the vehicle developed an intermittent B174C fault with the SRS light illuminating in damp weather. Inspection found green copper corrosion on the terminals inside the left rear seat side airbag connector (beneath the seat backrest), caused by water ingress during car washing that did not dry. Contact resistance between the terminals measured 12Ω. Resolution: Cleaned the terminals with electronic cleaner, applied conductive protective grease, replaced the connector housing with a waterproof type, and re-crimped the terminals. The fault has not recurred.
Original source ↗
BYD DTC AI Analysis

BYD Han EV airbag igniter aging high-resistance fault

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Vehicle under collision repair (left rear side impact). After replacing the left rear quarter panel and C-pillar trim, the SRS warning light set DTC B174C. The replacement salvage airbag resistance measured 6.8 Ω (normal: 2.3 Ω). Long-term storage moisture caused chemical degradation inside the igniter. Installed a new left rear side airbag (part no. SA2E-62766-00), performed module configuration programming and system calibration. Resistance returned to normal 2.1 Ω, fault cleared.
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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.