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B2AB4-1D

This DTC indicates the electric air conditioning compressor (E-Compressor) internal high-voltage drive circuit detected an abnormal overcurrent condition — Atto 3

Thermal Management System

This DTC indicates the electric air conditioning compressor (E-Compressor) internal high-voltage drive circuit detected an abnormal overcurrent condition.

Specifically, the compressor's built-in permanent magnet synchronous motor (PMSM) drive current exceeded the IGBT power module safety threshold (typically 30-50A, depending on the vehicle model).

This fault involves the compressor internal high-voltage inverter module, motor winding insulation condition, or an abnormal mechanical load.

The compressor control unit (ECU) triggers this fault when it detects, via the Hall current sensor, that the instantaneous phase current continuously exceeds the calibrated threshold (e.g., 60A/100ms or 80A/10ms).

This fault initiates an automatic compressor protective shutdown, affecting air conditioning cooling and battery thermal management functions.

In extreme cases, it may damage the high-voltage fuse or high-voltage wiring harness.

4
Cases Logged
Real-World Cases
BYD DTC AI Analysis

2019 Qin Pro EV: Air conditioning suddenly stopped working while driving

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At 30,000 km, the air conditioning suddenly stopped cooling while driving and the dashboard displayed "Thermal Management System Fault". The VDS scan reported codes B2AB4-1D and B2AB349 (internal temperature sensor fault). The data stream showed the compressor current spiked to 85A immediately before the failure (rated maximum 45A). Disassembly revealed the scroll plates inside the compressor had worn due to oil starvation, causing excessive motor load that triggered overcurrent protection. Replaced the compressor assembly, flushed the air conditioning lines, and added 150ml POE refrigeration oil and 450g refrigerant. Fault resolved.
BYD DTC AI Analysis

Batch failure of A/C compressor IGBT modules in new Yuan Plus vehicles

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After sitting overnight, the air conditioning failed to start and set DTC B2AB4-1D. Compressor three-phase winding resistance measured normal (1.2Ω) and insulation resistance >1000MΩ, ruling out motor failure. Disconnected the compressor high-voltage harness; controller-side bus voltage measured normal (320V), but a 'pop' came from inside the controller at power-up. Disassembled the compressor controller (without disassembling the compressor unit) and found the IGBT module (part number FS820R08A6P2B) collector-emitter shorted due to breakdown. Replaced the compressor controller board (BYD part number HAEG-8103020), clearing the fault.
Original source ↗
BYD DTC AI Analysis

Refrigerant leak caused compressor overcurrent in BYD Qin EV300

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Owner reported the A/C cooling gradually deteriorated until complete failure. Inspection found frost on the low-pressure line with abnormal pressures (low 0.05 MPa, high 0.8 MPa). Diagnosed as severe refrigerant leak. After recharging, the compressor ran for 5 minutes before setting DTC B2AB4-1D and shutting down. Prolonged operation with insufficient refrigerant caused inadequate internal lubrication; dry friction increased resistance in the scroll plates. Replaced the compressor and repaired the leak at the evaporator inlet pipe joint. Charged refrigerant and compressor oil to specification; system now operates normally.
Original source ↗
BYD DTC AI Analysis

Qin Pro DM compressor control board current sampling abnormality

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The vehicle intermittently sets DTC B2AB4-1D. When the fault occurs, the compressor immediately shuts down, but may operate normally after restarting. Monitored the compressor three-phase current waveforms with an oscilloscope and found high-frequency noise on the W-phase current sampling signal. Disassembled the compressor controller and found a dry solder joint on the current sampling resistor (0.005Ω/3W), causing the sampling voltage to drift and the ECU to falsely detect overcurrent. Resoldered the sampling resistor and applied conformal coating. The fault has not reoccurred.
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.