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B2AB6-4B

DTC B2AB6-4B indicates the Electric A/C Compressor internal temperature sensor detects a temperature outside the normal operating range (typically >120°C or an abnormal temperature rise rate) — Atto 3

Thermal Management System

DTC B2AB6-4B indicates the Electric A/C Compressor internal temperature sensor detects a temperature outside the normal operating range (typically >120°C or an abnormal temperature rise rate).

This fault indicates the compressor internal thermal protection mechanism triggered.

Electrical insulation failure, mechanical friction overheating, abnormal controller drive, or refrigerant circulation faults can cause this condition.

This fault disables the air conditioning cooling function.

In severe cases, thermal management system anomalies may trigger the 'EV Function Limited' protection mode, restricting the vehicle's pure electric driving capability.

It typically does not affect high-voltage system safety.

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Cases Logged
Real-World Cases
BYD DTC AI Analysis

Compressor insulation failure caused abnormal temperature

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AC not cooling; vents blowing ambient air. After driving for some time, the instrument cluster displayed 'EV Function Limited'. Diagnosis found DTCs B2AB573 (Operation Unsuccessful) and B2AB64B (Internal Temperature Abnormal). Measured refrigerant compressor insulation resistance to ground at 0.00MΩ, indicating internal insulation failure. System pressures were also abnormal: high-side pressure high, low-side pressure low. Replaced the electric refrigerant compressor and AC thermostat, recharged the refrigerant, and eliminated the fault.
Original source ↗
BYD DTC AI Analysis

Compressor controller fault caused recurring temperature abnormalities

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Two days after compressor replacement, the vehicle again failed to cool. Scanned DTCs B2AB41D (excessive internal current), B2AB64B (abnormal internal temperature), and B2AB774 (abnormal speed). Data analysis showed the compressor running continuously at high speed with abnormal thermostat opening. Confirmed the AC controller failed, causing abnormal compressor operation. Replaced the AC controller and cross-verified on another vehicle, completely resolving the fault.
Original source ↗
BYD DTC AI Analysis

Air conditioning system combined fault (thermostat and controller)

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Air conditioning completely failed with no cooling. Retrieved fault codes B2AB573 (operation unsuccessful) and B2AB64B (internal temperature abnormal). Troubleshooting found abnormal insulation resistance to ground on the refrigerant compressor, with high-side pressure too high and low-side pressure too low. Replaced the thermostat and recharged refrigerant initially, but the fault persisted. Further inspection found the air conditioning controller also needed replacement. Replaced the controller, thermostat, and refrigerant to fully resolve.
Original source ↗
BYD DTC AI Analysis

Scroll plate design defect causes abnormal internal temperature

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Poor AC cooling: high low-side pressure, low high-side pressure, ice on the low-pressure line, no cooling. Removed the compressor and inspected the scroll plates. Found mirror-like surface finish but no internal seal ring (design defect), causing gas leakage and internal bypass that reduced efficiency and created abnormal internal temperatures. Replaced the scroll plates with an improved design featuring seal rings, charged with EV-specific POE refrigeration oil, reinstalled the compressor to the original position, and tested. Outlet temperature dropped to 4°C and cooling performance restored.
Original source ↗
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.