BYD ATTO 3 (e-Platform 3.0) B2A0803 Evaporator Outlet Refrigerant Pressure Sensor Open Circuit

B2A0803 indicates an open circuit has been detected in the evaporator outlet refrigerant pressure sensor circuit. The fault affects the air-conditioning system’s refrigerant pressure monitoring, which provides the control system with pressure information used to regulate compressor operation and protect the refrigerant circuit. The BYD ATTO 3 uses BYD’s e-Platform 3.0 architecture, with this generation introduced from 2022 and continuing onward.

Symptoms

• Air conditioner does not cool effectively
• A/C cooling may be intermittent
• Electric compressor may not operate
• Compressor operation may be limited as a protective measure
• Climate control warning may be displayed
• Cabin temperature remains higher than requested
• Refrigerant pressure readings may be missing or implausible
• B2A0803 stored in the HVAC or related control system

Possible Causes

• Open circuit in the evaporator outlet pressure sensor wiring
• Faulty refrigerant pressure sensor
• Loose or disconnected sensor connector
• Damaged connector terminals
• Corrosion or poor electrical contact
• Damaged wiring or harness
• Sensor power or ground circuit fault
• Internal sensor failure
• Low or unstable 12V auxiliary voltage
• HVAC control-module fault
• Refrigerant circuit or pressure abnormality causing related system faults

Diagnosis

Diagnosis should begin by confirming B2A0803 and checking the pressure sensor’s live data for missing or implausible readings. The sensor power and ground circuits, wiring continuity, connector condition, signal circuit, and HVAC control-module data should then be evaluated against manufacturer specifications. Refrigerant pressure and system operating conditions should also be considered to distinguish an electrical sensor-circuit fault from an actual refrigerant-system abnormality.

Because the system uses an electric high-voltage compressor, appropriate EV safety procedures should be followed during diagnosis. Accurate diagnosis is particularly important when parts availability and repair costs are considerations for New Zealand vehicle owners.

Accurately diagnosing this fault often requires manufacturer testing procedures, wiring diagrams, connector pinouts, specifications, and system calibration information. Access to the factory service manual significantly reduces diagnostic time and helps prevent unnecessary parts replacement.

Applicable Years

2022, 2023, 2024, 2025, 2026, onwards

To order the correct OEM Service and Repair Manual for your BYD ATTO 3, submit your request using the form below and our team will provide the ordering details.