AU
B132817

This fault code indicates the supply voltage or feedback voltage of the heat pipe electric water pump in the Battery Thermal Management System (BTMS) exceeds the calibrated threshold (typically exceeding 16V in the low-voltage system, or abnormal high-voltage sampling) — Atto 3

Thermal Management System

This fault code indicates the supply voltage or feedback voltage of the heat pipe electric water pump in the Battery Thermal Management System (BTMS) exceeds the calibrated threshold (typically exceeding 16V in the low-voltage system, or abnormal high-voltage sampling).

In models like the BYD Qin EV, the VCU or Thermal Management Controller (TMS) drives this water pump via a PWM signal (100-900Hz).

Upon fault trigger, the system records freeze-frame voltage data.

Overvoltage may cause water pump drive MOSFET breakdown and motor winding insulation aging, triggering battery thermal management derating protection (limiting charge and discharge power).

Prolonged overvoltage may cause insufficient battery pack heat dissipation, but typically does not affect driving safety before triggering overheat protection.

Differentiate between genuine overvoltage (power supply system fault) and false overvoltage (sampling circuit or sensor fault).

5
Cases Logged
5
Causes
Likely Causes — Atto 3
  • 1DC-DC converter or low-voltage charging system fault causing abnormal 12V system voltage rise (exceeding 15.5V).
  • 2Partial short circuit or insulation failure in the internal windings of the battery coolant electric water pump, causing abnormal back electromotive force.
  • 3Poor contact in the water pump power supply wiring or connector (oxidized or loose) creates a high-resistance point, causing voltage spikes.
  • 4Thermal management controller (TMS) or VCU internal voltage sampling circuit fault (ADC module damage, reference voltage drift)
  • 5High-voltage system insulation fault couples into the low-voltage control circuit, causing signal interference or increased induced voltage.
What To Do
  • 1
    Use the VDS2000/3000 diagnostic tool to read complete fault codes and freeze frame data. Record the water pump voltage, duty cycle, coolant temperature, and ambient temperature at the time of the fault.
  • 2
    Check the low-voltage battery static voltage and dynamic charging voltage. Measure the DC-DC output terminal voltage and verify it is within the normal 13.5-14.5V range to rule out charging system overvoltage.
  • 3
    Check the water pump power supply fuse (usually 30A), relay, and wiring harness connector. Measure the voltage at the water pump connector B+/B- terminals with the ignition ON and verify there are no poor connections or oxidation.
  • 4
    Disconnect the water pump connector. Use a multimeter to measure the water pump winding resistance (normal range: 2-10 Ω, depending on the specific model) and insulation resistance (must be >20 MΩ) to check for internal short circuits.
  • 5
    Use an oscilloscope to check the water pump PWM control signal waveform. Verify the frequency, duty cycle, and voltage amplitude are normal to rule out abnormal controller output.
  • 6
    Compare the no-load current of the new and old water pump assemblies (normal: <5A). If the current is abnormal or the resistance deviation is >20%, replace the water pump.
  • 7
    Check the thermal management controller software version. If a relevant Technical Service Bulletin (TSB) exists, update to the latest software version to eliminate false codes.
  • 8
    Clear the fault code, perform a 30-minute dynamic road test (including fast charging and hard acceleration), and confirm the fault does not recur.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Excessive DC-DC converter output voltage caused water pump overvoltage alarm.

✓
A 2019 Qin EV with 80,000 km had an intermittent cooling system fault light. Scanned DTC B132817. Freeze frame showed water pump voltage at 16.8V when the fault occurred. Checked DC-DC output and found idle voltage at 15.9V. Determined a faulty internal voltage regulation module in the DC-DC converter. Replaced the DC-DC converter. System voltage returned to normal 13.8V. Fault code cleared and has not returned.
BYD DTC AI AnalysisFrom Chinese market (translated)

Water pump connector oxidation caused abnormal contact resistance

✓
After water ingress, DTC B132817 set. Supply voltage at the water pump measured 14.2V (normal), but the connector showed significant green corrosion. Cleaned the B23 connector (water pump power plug) and applied conductive paste; contact voltage drop fell from 1.2V to 0.1V, clearing the fault. Root cause: oxidation created a high-impedance point that generated voltage spikes, triggering the overvoltage protection.
BYD DTC AI AnalysisFrom Chinese market (translated)

Thermal management controller software false overvoltage alarm

✓
The 2020 Qin EV showed intermittent DTC B132817 after an OTA update. The measured water pump supply voltage was normal at 14.0V, but the data stream showed the VCU sampling voltage randomly jumping to 17V. A technical service bulletin confirmed an ADC sampling algorithm defect in this production batch. After upgrading the thermal management controller software to V2.3.1, the sampling values stabilised and the fault cleared.
BYD DTC AI AnalysisFrom Chinese market (translated)

Battery coolant pump internally short-circuited and burned out

✓
While driving, the vehicle suddenly limited power. Read DTCs and found B132817 along with B132971 (locked rotor). Disassembled the water pump and found the internal impeller jammed, causing the motor to lock up. The surge in winding current triggered overvoltage protection. After replacing the water pump assembly and flushing the thermal management lines (found heavy scale buildup), the system returned to normal. Recommend also replacing coolant and cleaning radiator.
BYD DTC AI AnalysisFrom Chinese market (translated)

Abnormal interference of the high-voltage interlock loop with low-voltage signals

✓
Found DTC B132817 after repairing the accident-damaged vehicle. Inspection found the high voltage interlock connector was not fully seated, causing abnormal high voltage system insulation monitoring and generating electromagnetic interference that coupled onto the water pump PWM signal line. After reseating the high voltage interlock connector and rewrapping the wiring harness, the fault code cleared and did not return. Always check the low voltage signal harness shield grounding after completing high voltage system repairs.
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]