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B132013

DTC B132013 is a specific fault within the thermal management/air conditioning subsystem (13) of the BYD body control system (B-Body) — Seal U

Thermal Management System

DTC B132013 is a specific fault within the thermal management/air conditioning subsystem (13) of the BYD body control system (B-Body).

The '20' designates the battery coolant temperature sensor or a related thermal management temperature sensor, and '13' indicates an open circuit.

This fault indicates the thermal management control unit (typically integrated into the Battery Management System (BMS) or air conditioning controller) detects a continuously high voltage on the coolant temperature sensor signal circuit (typically near the 5V reference voltage) and cannot obtain a valid temperature resistance signal.

As a result, the thermal management system enters fail-safe mode.

The system forcibly limits charge and discharge power, disables DC fast charging, and activates the maximum cooling strategy (high-speed fan and full-speed water pump operation).

In extreme cases, the system triggers a 'powertrain fault' and prevents the vehicle from entering the Ready state to prevent overheating damage to the battery or drive motor caused by the loss of temperature monitoring.

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Cases Logged
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Causes
Likely Causes — Seal U
  • 1The internal NTC thermistor element in the sensor body is broken or has an open circuit, causing infinite resistance (normal resistance at ambient temperature is 2kΩ-10kΩ, depending on the model's calibrated temperature curve).
  • 2Loose low-voltage wiring harness connector, backed-out pins, or oxidized/corroded pins causing poor contact due to vibration or water ingress, especially at the low-voltage plug near the battery pack high-voltage connector.
  • 3Physical damage to the wiring harness, including insulation aging and cracking from high front compartment temperatures, harness chafing against body sheet metal, or rodents chewing through the signal wire.
  • 4Sensor power supply or ground circuit fault, such as a 5V reference voltage circuit short to ground triggering a protective ECU disconnection, or excessive ground return circuit resistance causing a false open circuit diagnosis.
  • 5Thermal management control unit (BMS or air conditioning controller) internal signal acquisition circuit fault, such as a burnt sampling resistor or damaged analog-to-digital converter.
What To Do
  • 1
    Use VDS or a dedicated diagnostic tool to read the DTC freeze frame data. Record the ambient temperature, battery temperature, and vehicle status when the fault occurred. Confirm whether it is a hard fault (currently present) or an intermittent fault (history code).
  • 2
    Visually inspect the coolant temperature sensor connector at the battery pack coolant outlet, PTC heater outlet, or plate heat exchanger outlet. Verify the connector latch is intact, secure, and shows no signs of water ingress or corrosion. If necessary, disconnect the connector to check for backed-out pins.
  • 3
    Disconnect the sensor connector and use a multimeter to measure the sensor resistance. At an ambient temperature of 25°C, the normal resistance is approximately 10 kΩ (refer to the temperature-resistance curve table in the repair manual). If the reading is infinity (OL), replace the sensor.
  • 4
    With the connector disconnected, measure the voltage on the wiring harness side. Expect a 5V reference voltage (Vref) and 0V ground. The signal wire voltage must be close to 5V (open-circuit voltage). If the voltage is abnormal, check wiring harness continuity between the sensor and the control unit, especially the harness passing through the front compartment and battery pack area.
  • 5
    Perform continuity and insulation tests on the wiring harness: measure the signal wire resistance between the sensor connector and the control unit connector. Resistance must be less than 1Ω, and insulation resistance to ground must be greater than 10MΩ. Inspect the bend points where the wiring harness passes through the firewall and the battery pack casing.
  • 6
    Perform sensor replacement verification: Use a known good sensor of the same model to perform a jumper test and check if the data stream returns to normal. If normal, the original sensor is faulty.
  • 7
    After repairing the wiring harness or replacing the sensor, clear the fault code and perform a road test (including various vehicle speeds and charge/discharge conditions). Monitor the thermal management data stream to verify the temperature display changes smoothly with operating conditions, confirming complete fault resolution.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

BYD Qin EV300: Loose battery pack connector caused intermittent open circuit

✓
A 2017 Qin EV300 with 80,000 km had an intermittent “Power System Fault”, especially after driving on rough roads. The scan tool showed current fault code B132013. Inspection of the coolant temperature sensor plug at the front of the battery pack revealed a broken lock clip. This prevented the connector from seating fully, and it would disconnect with slight vibration. Replaced the waterproof plug housing (complete with lock clip), re-crimped the harness terminals, and applied BYD conductive paste (Kontakt 61). Fault completely resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Front compartment wiring harness chafed against bracket, causing signal wire to break

✓
After collision repair, fault code B132013 persisted and could not be cleared. Inspection found the wiring harness had been improperly secured during the accident repair, causing the battery cooling system water temperature sensor harness to chafe against the front chassis rail bracket. Prolonged friction broke a single copper strand, while the outer insulation remained intact, creating a hidden open circuit. Repair: Stripped back the harness insulation to locate the break. Repaired the wiring using waterproof heat-shrink tubing. Rerouted the harness, added corrugated tubing for protection, and secured it in the original factory clip positions.
BYD DTC AI AnalysisFrom Chinese market (translated)

Sensor thermal aging caused an open circuit under high-temperature operating conditions.

✓
The vehicle developed a fault after running the PTC heater for a while in winter, although cold starts were normal. When the sensor was heated with a heat gun, its resistance suddenly jumped to open circuit at about 60°C and recovered after cooling. This indicates thermal fatigue fracture of the internal NTC element. Replacing the battery coolant temperature sensor (part no. BYD-3726010-XX) fixed the fault. Also check whether degraded coolant is causing abnormal heat transfer to the sensor.
BYD DTC AI AnalysisFrom Chinese market (translated)

Connector pins oxidised after water ingress, causing excessive contact resistance

✓
After driving through water, the vehicle developed a fault. The scan tool showed the coolant temperature sensor signal voltage was 4.9V (near the open circuit threshold). We disconnected the coolant temperature sensor connector under the battery pack and found mud and water had gotten inside. The pins were oxidised and blackened, creating high resistance that caused the control unit to misinterpret the condition as an open circuit. We thoroughly cleaned the connector with electronic cleaner, sanded the pins down to bare metal, and applied a protective coating. We also replaced the sealing ring and, where needed, applied sealant around the connector to improve waterproofing.
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]