AU
B132213

This fault code indicates an open circuit in the signal circuit of the pressure/temperature sensor at the Plate Heat Exchanger (PHE) outlet — Seal U

Thermal Management System

This fault code indicates an open circuit in the signal circuit of the pressure/temperature sensor at the Plate Heat Exchanger (PHE) outlet.

In the BYD heat pump thermal management system, the Plate Heat Exchanger is the core component for heat exchange between the refrigerant and the motor coolant.

The outlet pressure sensor monitors the refrigerant pressure (or integrated temperature) after heat exchange, providing closed-loop control data for the Electronic Expansion Valve (EXV) and the electric compressor.

An open circuit fault indicates the control unit (air conditioning controller or thermal management module) detects a continuous sensor signal voltage above 4.8V (typically corresponding to an unshunted 5V reference voltage).

Without real-time pressure data, the system triggers thermal management protection mode.

This mode disables the heat pump function, limits motor power output, and in extreme cases, prohibits high-voltage power-up to prevent heat exchanger overpressure damage or abnormal refrigerant circulation.

5
Cases Logged
5
Causes
Likely Causes — Seal U
  • 1Sensor harness physical damage: High temperatures and vibration in the engine compartment cause the harness insulation to age and crack, or prolonged chafing against sharp metal edges breaks the copper core wires. This commonly occurs due to improper harness fastening after accident repairs.
  • 2Poor connector contact: Backed out or oxidized internal terminals (common after water ingress) or a loose locking tab in the sensor 2-pin or 3-pin connector cause an open signal circuit. Measurement shows infinite resistance between the pins.
  • 3Internal sensor body open circuit: Refrigerant pressure shock or long-term thermal cycling fatigue cracks solder joints on the pressure-sensitive element or internal PCB, resulting in zero current draw.
  • 4Control unit side fault: A loose connector, bent pins, or an open internal sampling resistor at the air conditioning controller or thermal management controller (TMS) prevents the 5V reference voltage from completing the circuit.
  • 5Wiring harness transition connector fault: Some models feature a transition connector (CJB or BJB) at the firewall or fender. Poor sealing at this location causes water ingress and corrosion, resulting in a signal wire open circuit at the transition point.
What To Do
  • 1
    Safety preparation and fault confirmation: Disconnect the high-voltage service disconnect and wait 5 minutes to discharge residual voltage; use the diagnostic tool to read the DTC and record freeze frame data; observe the pressure display value (an open circuit typically displays 4.9-5.0V or an out-of-range value of -40℃); clear the fault code, run the air conditioning system, and observe if the fault immediately reappears.
  • 2
    Sensor body inspection: Locate the pressure/temperature sensor at the plate heat exchanger outlet (usually on the top or side of the heat exchanger, with a 2-3 wire harness). Disconnect the connector and measure the resistance between the sensor terminals (normally about 2-3 kΩ at 25°C; refer to the workshop manual for exact values). If the resistance is infinite, replace the sensor. Measure the supply voltage (should be 5V ± 0.25V) to confirm normal reference voltage output.
  • 3
    Harness continuity check: Use a multimeter to measure harness continuity between the sensor connector and the control unit, focusing on the signal wire (usually the pressure signal pin) and the ground wire. Inspect the entire harness for signs of crushing or abrasion, paying special attention to the firewall pass-through and high-temperature areas near the exhaust pipe. Measure the harness insulation resistance to ground; it must be greater than 10MΩ.
  • 4
    Connector integrity repair: Check if the connector sealing ring is missing or aged, and replace the waterproof plug if necessary; use a dedicated terminal release tool to check terminal retention force, and replace the connector assembly or female terminal if loose; clean oxidized pins, apply conductive grease, then reconnect and listen for the locking click.
  • 5
    System verification and finalization: After repair, reconnect all components, power on the vehicle, and read the data stream. Confirm the pressure reading matches the actual ambient temperature (static pressure approximately 0.6-0.8MPa@25℃). Start heat pump mode and observe the dynamic pressure response as the electronic expansion valve opening changes. Perform a road test or hoist test to confirm no intermittent open circuits exist before vehicle delivery.
Real-World Cases
BYD DTC AI AnalysisFrom Chinese market (translated)

Intermittent open circuit in plate heat exchanger pressure sensor on Qin Pro DM after wading

✓
The air conditioning stopped producing heat after the vehicle drove through water. DTC B132213 stored. Inspection revealed water inside the plate heat exchanger outlet pressure sensor connector, with the pins oxidised and blackened. The connector seal failed due to water surge while wading. Cleaned the oxidised pins, replaced the seal, and fitted waterproof corrugated tubing to the wiring harness. Fault resolved.
BYD DTC AI AnalysisFrom Chinese market (translated)

Qin EV300: Wiring harness wear caused open circuit after accident repair

✓
Following right-front collision repairs, B132213 would set intermittently while driving. Inspection found the accident repair had incorrectly secured the harness, causing the plate heat exchanger sensor wiring to chafe against the sharp edge of the right front chassis rail. The insulation wore through and the signal wire (one of three copper cores) completely fractured. Repaired the damaged harness, sealed with heat shrink tubing, re-routed and secured the clips to specification, and fitted a protective sleeve to prevent chafing.
BYD DTC AI AnalysisFrom Chinese market (translated)

False open circuit caused by a loose thermal management controller connector

✓
Vehicle has no accident history. Heat pump system suddenly failed. Diagnostics showed the pressure sensor had normal power supply but the signal voltage remained at 5V. Investigation revealed the 32-pin connector on the thermal management controller (under the centre console) was not fully locked, possibly loosened when stepped on during transport or repairs. Reseated and secured the connector; fault cleared.
BYD DTC AI AnalysisFrom Chinese market (translated)

Cracked internal PCB in sensor body caused open circuit at low temperatures

✓
In cold northern winter weather, the vehicle could not start the heat pump; the fault disappeared in a warm garage. Disassembly revealed that the internal PCB solder joint of the plate heat exchanger outlet pressure sensor cracked due to low-temperature contraction, causing a signal open circuit. Replaced the OEM pressure-temperature sensor assembly and verified the fault was cleared in a -20°C environmental chamber.
BYD DTC AI AnalysisFrom Chinese market (translated)

Hidden open circuit caused by water ingress and corrosion in the adapter plug

✓
DTC appeared intermittently. Tapping the inner fender wiring harness reproduced the fault. Inspection found water ingress at the firewall connector (BJ02) due to perished sealing rubber. The pressure sensor signal wire had corroded and broken at the connector terminal. Replaced the connector assembly, repaired the corroded wiring harness, and resealed the firewall penetration with sealant.
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]