AU
B132A00

This fault code indicates the electric water pump in the battery thermal management system (typically integrated into the battery thermal pipe cooling circuit) is dry running — Atto 3

Thermal Management System

This fault code indicates the electric water pump in the battery thermal management system (typically integrated into the battery thermal pipe cooling circuit) is dry running.

The system triggers this fault when the pump motor receives a PWM operating command from the TMS (Thermal Management Controller) or A/C controller and powers on to rotate, but the impeller fails to generate effective coolant flow.

The system also triggers this fault if the actual speed detected by the speed feedback sensor (Hall effect sensor) deviates from the target speed by more than the threshold (typically >30%) for 5–10 seconds.

This fault functions as flow abnormality protection.

The condition can cause insufficient battery pack heat dissipation and excessive cell temperature differences, triggering reduced power operation (torque limiting).

In extreme cases, it triggers a battery overheat warning.

Causes include dry running due to a lack of coolant, impeller shaft breakage, magnetic coupling slip, cavitation, or seized bearings.

3
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1Low battery coolant level or system leak (e.g., at thermal pipe joints or battery pack cooling plate seals), causing the water pump to draw in air and run dry.
  • 2Internal magnetic coupling failure of the electric water pump impeller (permanent magnet rotor separated from the impeller) or broken impeller shaft, causing the motor to spin freely while the impeller does not rotate.
  • 3Water pump power supply circuit fault, including blown fuse F2/26, disconnected high-voltage interlock, or poor contact at connector CN112 causing a voltage drop.
  • 4Open circuit or short to ground in the water pump speed feedback signal wire (usually connects to air conditioning controller Pin 23/24), or internal Hall sensor damage, causing the controller to falsely detect a stopped pump.
  • 5Incomplete bleeding of the thermal management system leaves significant air locks in the cooling circuit, causing the water pump to run without effective flow.
What To Do
  • 1
    VDS Diagnosis: Connect the VDS diagnostic tool, read the DTC freeze frame, and check the 'battery thermal management water pump target speed' and 'actual speed' data streams. Verify if the actual speed is 0 or significantly below the target value (<100rpm).
  • 2
    Cooling system check: Verify the expansion tank coolant level is between MIN and MAX. Inspect the battery pack cooling lines, heat pipe heat exchanger, and water pump body for coolant crystallization (signs of leakage). If necessary, pressurize and hold pressure (150kPa, 10 minutes) to locate leaks.
  • 3
    Electrical measurement: Disconnect battery thermal pipe water pump connector B12. Measure the voltage between Pin 1 (B+) and Pin 2 (GND). The voltage must be 12V ± 0.5V (or high-voltage system voltage, depending on vehicle model). Measure Pin 3 (PWM control) for a square wave signal with a 5-95% duty cycle. Check Pin 4 (feedback) for a pulse signal.
  • 4
    Mechanical inspection: Perform the water pump active test and listen for the operating sound. If you hear a high-frequency hum but no liquid flow sound, remove and inspect the water pump outlet pipe to check for coolant flow. If no coolant flows out, replace the water pump assembly.
  • 5
    System reset: After repair, fill with specified low-conductivity coolant (such as BYD dedicated coolant). Perform the 'Cooling System Bleeding' procedure (use VDS to intermittently drive the water pump to purge air). Clear the fault code and road test to confirm.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin EV coolant leak caused water pump to run dry

✓
The dashboard displayed a "Powertrain Fault" warning. DTC B132A00 stored. Inspection found coolant leaking from the hose connection at the front of the battery pack, and the expansion tank was empty. After topping up the coolant, the water pump ran but the upper hose had no pressure. Disassembling the water pump revealed the impeller had warped from overheating due to prolonged dry running. Replaced the water pump and seals, refilled the coolant, and bled the system to resolve the fault. Root cause: a loose clamp at the connection caused a slow leak, while the coolant level sensor failed to trigger a warning promptly.
BYD DTC AI AnalysisFrom Chinese market (translated)

Thermal management coolant pump magnetic coupling slip fault

✓
2019 Qin EV frequently logged thermal management faults during fast charging. VDS showed commanded pump speed 3000 rpm and actual speed 0 rpm. Disassembled and inspected the battery coolant pump. The internal magnetic coupling had developed excessive air gap from prolonged vibration, causing the motor rotor to spin while the impeller remained stationary. After replacing the electric water pump assembly, the measured inlet‑outlet temperature differential recovered from 0°C to the normal 8–12°C range, and the fault code did not reappear.
BYD DTC AI AnalysisFrom Chinese market (translated)

Water ingress corroded the wiring harness connector, causing signal abnormality.

✓
Vehicle stored B132A00 after driving through water. Found green corrosion inside battery water pump connector B12 at the left front chassis rail. Pin 4, the speed feedback pin, oxidised and interrupted the signal. Cleaned the connector, applied conductive paste, verified normal harness continuity, and refitted the connector. No faults returned during one-month follow-up. Determined inadequate sealing during water ingress caused the pin corrosion.
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: Official This information is for reference only. Always consult a qualified technician for diagnosis and repair. Do not attempt high-voltage system repairs yourself. Sources: [1]