AU
B2AB41D

This fault code indicates the internal drive current of the thermal management system electric scroll compressor (E-Compressor) exceeds the safety threshold set by the MCU (microcontroller unit) (typically peak current >45A or sustained RMS current >15A) — Qin Plus

Thermal Management System

This fault code indicates the internal drive current of the thermal management system electric scroll compressor (E-Compressor) exceeds the safety threshold set by the MCU (microcontroller unit) (typically peak current >45A or sustained RMS current >15A).

This hardware-level protection fault indicates the compressor permanent magnet synchronous motor (PMSM) or its integrated controller (including the IPM intelligent power module) detects abnormal current consumption.

During compressor start-up or operation, the controller triggers this fault if Hall sensors detect a three-phase current imbalance exceeding 10%, or if the instantaneous DC bus current exceeds the calibrated limit (approximately 22-25A) for over 100ms.

The compressor stops immediately to protect the IGBT power devices, affecting cabin air conditioning cooling/heating and battery pack liquid cooling functions.

A prolonged fault may burn out the compressor controller or blow the high-voltage fuse (typically 30A-40A).

The B2AB41D fault code on the Qin Plus indicates excessive internal drive current in the electric scroll compressor for the thermal management system. Severity is medium, as the compressor may shut down to protect high-voltage components, affecting cabin climate control and battery cooling. Common causes include compressor motor winding insulation failure or a faulty integrated controller/IPM. The recommended fix is to visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
4
Cases Logged
5
Causes
Likely Causes — Qin Plus
  • 1Inter-turn short circuit in the electric compressor internal motor winding, or degraded phase-to-phase insulation (insulation resistance <20MΩ), causing an abnormal increase in electromagnetic load and operating current spikes.
  • 2Compressor integrated controller fault, including IGBT breakdown in the IPM (Intelligent Power Module), current sampling resistor (shunt resistor) drift, or a gate drive circuit abnormality causing three-phase drive waveform distortion.
  • 3Excessive mechanical load on the air conditioning system, such as refrigerant overcharge (exceeding the standard value of 550g±25g), blocked receiver-drier/expansion valve causing excessive high-side pressure (>2.5MPa), internal compressor mechanical seizure, or lack of refrigerant oil (POE oil) causing poor lubrication.
  • 4High-voltage power supply circuit abnormality, including battery pack contactor ablation causing voltage drop (<320VDC), increased high-voltage wiring harness contact resistance (>10mΩ) causing voltage fluctuation, or EMC interference causing current sampling signal distortion.
  • 5Thermal management control strategy or software calibration defects, such as start-up current ramp control failure, abnormal closed-loop speed PID parameters causing current surges, or refrigerant migration causing liquid slugging during sharp ambient temperature drops.
What To Do
  • 1
    Use the VDS2000/3000 diagnostic tool to read the complete fault codes and freeze frame data. Specifically record the following parameters at the time of the fault: compressor speed (rpm), high-voltage bus voltage (V), three-phase current values (A), refrigerant high- and low-side pressures (kPa), IGBT temperature (°C), and fault occurrence count (Trip Counter).
  • 2
    Perform the standard high-voltage power-down procedure (turn off the ignition switch, disconnect the low-voltage battery negative terminal, and wait 5 minutes). Wear CAT III 1000V insulated gloves and use an insulation resistance tester to measure the insulation resistance between the compressor high-voltage input terminal and the vehicle body (standard: >500MΩ).
  • 3
    Check A/C system static pressure (0.9–1.1 MPa at 25°C ambient temperature). Use a manifold gauge to check dynamic high and low side pressures (normal low pressure: 0.15–0.25 MPa; high pressure: 1.3–1.6 MPa). Verify no ice blockage, debris blockage, or excessive refrigerant. Check the sight glass to verify refrigerant oil color and foam condition.
  • 4
    Disconnect the compressor low-voltage connector (usually 8-pin or 12-pin). Measure the DC resistance of the three-phase windings (U-V-W) using a micro-ohmmeter (standard value: 0.8-1.5 Ω at 20°C) and calculate the three-phase imbalance (must be <5%). Measure the insulation resistance of each phase to the housing using a megohmmeter (must be >20 MΩ).
  • 5
    Check the continuity of the High Voltage Interlock Loop (HVIL), measure the voltage drop across the high-voltage contactor contacts (should be <0.1V), verify the compressor high-voltage wiring harness shield has a good ground connection, and confirm the supply voltage is within the 320-420VDC range with no severe fluctuations (ripple <5%).
  • 6
    If winding resistance is abnormal or insulation fails, replace the electric compressor assembly (part number BC-8103020E or similar). For refrigerant issues, recover the refrigerant using a recovery machine, replace the desiccant, evacuate the system to -0.1 MPa, and hold pressure for 15 minutes. Recharge with the standard amount (450–550 g, depending on the model) of R134a or R1234yf and the corresponding compressor oil (approximately 120–150 ml).
  • 7
    After replacement, perform the compressor self-learning procedure (if applicable). Run an active test using the diagnostic tool to verify the compressor operates normally across the full speed range (1000-6000rpm), current remains stable within the 3-12A range, and there is no abnormal noise. Perform a 30-minute road test to verify the thermal management function and confirm the fault code does not reappear.
Real-World Cases
BYD DTC AI Analysis

Qin EV compressor winding insulation degradation causes intermittent overcurrent

✓
2019 BYD Qin EV, 68,000 km. Instrument cluster intermittently illuminated "Air Conditioning System Fault" warning. Retrieved DTC B2AB41D. Freeze frame showed compressor at 3,200 rpm drawing 18.5A (exceeding 15A calibration value) when fault occurred. Fault cleared after vehicle cooled while parked, but returned after 30 minutes of driving. Disassembly found compressor three-phase winding-to-housing insulation resistance was 50MΩ cold (normal) but dropped to 8MΩ at 60°C with heat gun (abnormal). Diagnosed as thermal degradation of enamelled wire insulation. Replaced electric compressor assembly, recovered and recharged refrigerant. Fault resolved.
BYD DTC AI Analysis

Ice blockage in refrigerant system triggered compressor overload protection

✓
2019 Qin EV. Heating worked normally in winter, but after 10 minutes of AC cooling, the system set DTC B2AB41D and the air conditioning stopped. Live data showed high-side pressure spiked instantly to 3.2 MPa (normal 1.5 MPa) before the fault, with current peaking at 26 A. Inspection revealed the receiver-drier had failed and system moisture was >500 ppm, causing ice blockage at the expansion valve. Recovered the refrigerant, replaced the receiver-drier and expansion valve, flushed the lines with nitrogen, evacuated and pressure-tested the system, then charged with the standard refrigerant amount and 30ml of fresh compressor oil. The fault has not returned.
BYD DTC AI Analysis

Burned high voltage contactor caused abnormal compressor current.

✓
After fast charging, DTC B2AB41D set along with the 'SRS fault' warning light. Diagnosis found the compressor controller detected excessive current fluctuation (ripple >5A). Measuring the HV line from the battery pack output to the compressor revealed burnt main positive contactor contacts with contact resistance of 15mΩ (normal <1mΩ). This dropped the voltage from 380V to 310V when the compressor started, causing the controller to pull abnormally high current to maintain power output. Replaced the battery pack main positive contactor (or the entire BDU - Battery Distribution Unit), cleaned the HV terminals, and resolved the fault.
BYD DTC AI Analysis

Drift in the compressor controller sampling resistor caused false fault reports.

✓
The vehicle had no actual air conditioning performance issues, yet the scan tool frequently logged historic DTC B2AB41D. Freeze frame showed only 12 A (below the actual threshold), but fault status read 'currently present'. Removed and inspected the compressor controller (did not disassemble the compressor body). Found a cold solder joint on the 5 mΩ precision shunt resistor in the current sampling circuit, causing sampling voltage drift. Resoldered the resistor and applied conformal coating, or calibrated the current sampling offset using an oscilloscope (wrote -0.8 A correction value via the scan tool). DTC cleared and did not recur.
Other Qin Plus Fault Codes
B1108For 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.B110913DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus overview →
Data confidence: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself.