AU
B132113

This DTC indicates an open circuit in the thermal management system Plate Heat Exchanger (PHE) coolant outlet temperature sensor — Seal U

Thermal Management System

This DTC indicates an open circuit in the thermal management system Plate Heat Exchanger (PHE) coolant outlet temperature sensor.

The PHE is the core heat exchange component between the battery liquid cooling system and the air conditioning refrigerant system.

The outlet temperature sensor monitors the post-exchange coolant temperature, providing a critical feedback signal for precise battery pack temperature control.

An open circuit fault causes the ECU to receive an out-of-range high-voltage signal (typically near the 5V reference voltage), preventing the system from obtaining accurate outlet temperature data.

This triggers thermal management system protection strategies, which may limit battery charge and discharge power, disable air conditioning cooling, or activate forced air cooling.

Extreme cases pose a risk of battery thermal runaway.

The sensor utilizes an NTC thermistor with a normal operating temperature range of -40°C to 150°C.

During an open circuit, the resistance approaches infinity.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Internal open circuit in the temperature sensor: Prolonged operation in high-temperature and high-humidity environments ages and breaks the internal thermistor element or causes cold solder joints, driving the resistance value to infinity.
  • 2Wiring harness open circuit or wear: The wiring harness connecting the sensor to the A/C controller/thermal management controller wears or breaks in the high-temperature, high-vibration area of the engine compartment, particularly at the corrugated conduit section near the plate heat exchanger.
  • 3Poor connector contact: Water ingress and oxidation at the sensor connector (usually located on the left side of the front compartment or at the battery pack cooling pipe connection), backed-out pins, or a loose retaining clip causing an intermittent connection.
  • 4Plate heat exchanger assembly connector damaged: pulling during cooling pipe removal damages the temperature sensor connector, or a failed connector seal causes internal corrosion.
  • 5Control unit input terminal fault: dry solder joint in the internal signal acquisition circuit of the air conditioning controller or battery management system (BMS), or burnt protection resistor, preventing sensor signal recognition.
What To Do
  • 1
    Use the VDS2000/3000 diagnostic tool to read the complete DTCs and freeze frame data. Record the ambient temperature, vehicle speed, and battery status at the time of the fault. Determine if the fault is intermittent.
  • 2
    Locate the sensor: On Qin series models, the sensor mounts to the plate heat exchanger coolant outlet pipe on the left side of the front compartment (black connector, 2-wire). Verify the connector is secure and inspect for signs of coolant leakage.
  • 3
    Electrical measurement: Turn off the ignition, disconnect the sensor connector, and measure the resistance between the two sensor terminals (standard value at 20°C: approx. 2.5 kΩ ±5%; an open circuit displays OL or infinity). If abnormal, replace the sensor.
  • 4
    Harness continuity test: Measure continuity from the sensor connector to the corresponding pin on the air conditioning controller (or thermal management module). Standard resistance must be less than 1 Ω. Measure for shorts to ground and power to confirm wiring harness integrity.
  • 5
    Voltage signal verification: Connect the connector, turn the ignition switch to ON, and measure the signal wire voltage (normally 0.5-4.5V varying with temperature; close to 5V reference voltage during an open circuit) to confirm the fault condition.
  • 6
    Component replacement and verification: Replace the temperature sensor with an OEM part (the part number usually includes 'Temperature'). Use a dedicated coolant hose clamp tool to ensure a proper seal. Fill the coolant, bleed the system, and clear the fault code. Perform a 20-minute dynamic road test and observe the 'PHE outlet temperature' value in the thermal management system data stream to verify it changes normally with operating conditions.
  • 7
    System function test: Turn on the air conditioning cooling and observe the battery cooling request signal. Confirm the temperature difference between the plate heat exchanger inlet and outlet is normal (usually 3-8°C) and verify the system generates no new temperature-related fault codes.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin EV300: Intermittent warning light while driving; loose connector clip.

✓
While driving at highway speeds, the instrument cluster suddenly displayed 'Thermal Management System Fault'. DTC read: B132113. Inspection found the plate heat exchanger outlet temperature sensor connector retaining clip had fractured, allowing the connector to come loose from driving vibrations. The connector sits on the left side of the front compartment near the wheel arch, making it vulnerable to water ingress when driving through water. Replaced the sensor connector (with wiring harness assembly), rewrapped the connection with waterproof tape, and resolved the fault. This case highlights the importance of checking wiring harness securing points in this area.
BYD DTC AI AnalysisFrom Chinese market (translated)

After accident repair, Qin Pro DM continuously reports open circuit. Pinched and damaged wiring harness.

✓
After front-end collision repairs, DTC B132113 set at every startup. Inspection found the front compartment harness incorrectly routed during the repair; the plate heat exchanger sensor harness was pinched between the condenser bracket and body, breaking both wires completely while the insulation stayed intact. Stripping back the harness revealed broken copper strands. After re-soldering the wires and insulating with heat-shrink tubing, the DTC cleared and the data stream returned to normal. During collision repairs, always inspect concealed harnesses carefully.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin Pro EV overheat protection activated during fast charging; sensor body damaged.

✓
The vehicle frequently displayed 'Battery Temperature Too High, Power Limited' during DC fast charging, with DTC B132113. Static measurement showed infinite sensor resistance at 20°C, confirming an internal open circuit. Replaced the plate heat exchanger outlet temperature sensor. (Use special tools to disconnect the quick-connect fitting to prevent coolant spray.) After replacement, temperature monitoring returned to normal during fast charging, restoring thermal management performance. The original sensor failed due to thermistor aging from long-term high-temperature cycling.
BYD DTC AI AnalysisFrom Chinese market (translated)

Intermittent fault after driving through water; internal oxidation of connector.

✓
Intermittent DTC B132113 appeared after driving through water, clearing in dry weather. Removed the sensor connector and found muddy water deposits inside, with pin surfaces oxidised green, causing contact resistance to intermittently increase to open circuit. Cleaned the connector with electronic cleaner, applied conductive grease, and replaced the seal. Check the front compartment drain holes for blockages to prevent water from accumulating and soaking this sensor connector.
BYD DTC AI AnalysisFrom Chinese market (translated)

Replaced the plate heat exchanger but failed to calibrate, causing false alarms.

✓
The workshop replaced the plate heat exchanger assembly and subsequently logged DTC B132113. Inspection found the sensor supplied with the new assembly had not been properly plugged into the wiring harness, and the plug alignment pin was damaged during installation. Additionally, on some Qin PRO models, after replacing this sensor, the diagnostic tool must be used to run the ‘Thermal Management System Sensor Calibration’ routine (menu path: Air Conditioning System → Special Functions → Temperature Sensor Calibration); otherwise, the system may misinterpret the signal as abnormal. Reconnecting the sensor and running the calibration cleared the fault.
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]