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 — Seal U

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 — Seal U
  • 1Low battery coolant level or system leaks (e.g., heat pipe joints, battery pack cooling plate seals) causing the water pump to draw in air and run dry.
  • 2Electric water pump internal impeller magnetic coupling failure (permanent magnet rotor separated from the impeller) or broken impeller shaft, causing the motor to spin freely while the impeller does not rotate.
  • 3Abnormal water pump power supply circuit, including blown F2/26 fuse, disconnected high-voltage interlock, or poor connection 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 a severe air lock 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 pipe water pump target speed' and 'Actual speed' data streams. Verify if the actual speed is 0 or far 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, apply and hold pressure (150 kPa, 10 minutes) to locate the leak point.
  • 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 the 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 the pump emits a high-frequency hum but no liquid flow sound, remove and inspect the water pump outlet pipe to check if coolant flows out. If no coolant flows out, replace the water pump assembly.
  • 5
    System reset: After repair, fill with dedicated low-conductivity coolant (such as BYD dedicated coolant), perform the 'Cooling System Bleeding' procedure (use VDS to intermittently run 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 Seal U 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.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.B1109DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.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.B110AThis DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.
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]