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B2A2413

DTC B2A2413 indicates the air conditioning control unit (AC ECU) detects an open circuit in the evaporator temperature sensor circuit — Qin Plus

Thermal Management System

DTC B2A2413 indicates the air conditioning control unit (AC ECU) detects an open circuit in the evaporator temperature sensor circuit.

This sensor, typically a negative temperature coefficient (NTC) thermistor, mounts to the evaporator fin surface inside the HVAC assembly.

It monitors real-time evaporator core temperature (normal operating range: 2–8°C).

If the sensor fails open, the wiring harness disconnects, or the connector has poor contact, the ECU detects a continuous 5V signal (or open-circuit voltage) and cannot obtain accurate evaporator temperature data.

The system then triggers a protection strategy.

To prevent evaporator icing, expansion, and core damage, the ECU forcibly disengages the compressor electromagnetic clutch or disables the electric compressor.

It may also default to a substitute value (such as 0°C or ambient temperature) to maintain limited cooling.

This causes air conditioning performance to degrade severely or fail completely.

Prolonged operation with this fault can cause frequent compressor cycling, abnormal battery pack thermal management (on models where the air conditioning system couples with battery cooling), and even high-voltage system insulation faults.

The B2A2413 fault code on the Qin Plus indicates an open circuit in the evaporator temperature sensor circuit. Severity is high because the AC ECU may disable the compressor to prevent evaporator icing or damage, causing weak or no cooling and possible battery thermal management issues. Common causes include a failed evaporator temperature sensor or a loose, corroded, or backed-out connector. Visit an authorised dealer for diagnosis and repair. Typical repair cost data is available.
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Cases Logged
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Causes
Likely Causes — Qin Plus
  • 1Evaporator temperature sensor internal open circuit: Prolonged exposure to a low-temperature, high-humidity environment causes the internal thermistor element to age and crack, or causes package seal failure, resulting in moisture ingress, corrosion, and an open circuit.
  • 2Loose harness connector or backed-out terminal: Prolonged driving on rough roads causes the sensor plug (usually a 2-pin white plug) on the passenger-side dashboard HVAC assembly to loosen, the locking tab to break, or the terminals to back out, resulting in poor contact.
  • 3Physical damage to the wiring harness: Metal edges cut the internal dashboard wiring harness during assembly or repair, or rodents severed the signal wire (the quiet motor compartment in EV models attracts rodents to chew wiring harnesses).
  • 4Pin corrosion: In coastal or high-humidity areas, an aging sensor connector seal allows moisture intrusion. This moisture oxidizes the copper pins, forming green verdigris and causing a high-resistance open circuit.
  • 5Air conditioning controller internal sampling circuit fault: Cold solder joints at the controller terminals or a damaged internal pull-up resistor prevent correct sensor signal identification (confirm this only after ruling out the first four items).
What To Do
  • 1
    Connect the VDS2000/Launch X431 diagnostic tool, enter the air conditioning system to read fault codes, and confirm B2A2413 is a current fault (Current DTC). Record the freeze frame data (Freeze Frame) to observe the ambient temperature and system status when the fault occurred.
  • 2
    Remove the front passenger side glove box or lower trim panel, locate the evaporator temperature sensor (between the fins on the right side of the evaporator core, typically a black plastic housing with a 2-wire connector), and visually inspect the connector for looseness and the wiring harness for damage.
  • 3
    Disconnect the sensor connector. Measure the resistance between the two sensor terminals using a multimeter. The normal value at 25°C ambient temperature is approximately 2.0-2.5 kΩ (refer to the temperature-resistance curve table in the repair manual for specific values). If the multimeter displays OL (open circuit) or the resistance is significantly higher than the nominal value, replace the sensor assembly.
  • 4
    If the sensor resistance is normal, measure the harness-side connector: Turn the ignition switch ON and measure the voltage between the signal wire and the ground wire; it should be the 5V reference voltage. Turn the ignition switch OFF and measure continuity from the sensor connector to the corresponding pin on the air conditioning controller; the resistance should be less than 1Ω. If there is no continuity, inspect the wiring harness in sections to locate the break.
  • 5
    Check the sensor connector pins for oxidation, spreading, or bending. If necessary, clean the pins with electrical contact cleaner and restore pin tension. Apply conductive grease and reconnect the plug. Ensure the locking tab clicks into place.
  • 6
    If the wiring harness and sensor are normal, remove the air conditioning controller. Inspect the corresponding controller terminals (usually specific pins in connector B23 or B24) for cold solder joints or corrosion. Replace the controller assembly if necessary.
  • 7
    After completing the repair, clear the fault code. Start the vehicle and set the air conditioning to maximum cooling mode. Observe the data stream to verify the evaporator temperature gradually drops from ambient temperature to the 2-5℃ range during the cooling process. Confirm no icing occurs and the fault code does not recur.
Real-World Cases
BYD DTC AI Analysis

Atto 3 air conditioning not cooling with fault code B2A2413

✓
2022 BYD Atto3 (Yuan Plus), 12,000 km. With the AC on, the vents blew only ambient air. No dashboard warnings appeared, but cooling failed. A scan tool showed current fault code B2A2413 (evaporator temperature sensor open circuit). Removing the passenger-side glovebox revealed the evaporator temperature sensor connector lock tab had broken; the connector worked loose and interrupted the signal. Without a temperature signal, the ECU entered protection mode and shut down the electric compressor. Re-securing the connector and reinforcing the wiring harness with cable ties restored operation: the data stream showed evaporator temperature dropping from 35°C to 4°C, and cooling returned to normal.
Original source ↗
BYD DTC AI Analysis

Qin Pro DM evaporator icing and low-pressure line frosting

✓
2019 BYD Qin Pro DM, 30,000 km. Owner reported AC cooling dropped sharply after 10 minutes. Found severe frost on the low-pressure line. Initially suspected a faulty expansion valve, but the scan showed intermittent DTC B2A2413. Inspection revealed the sensor harness chafed through at the firewall by a retaining clip. 80% of the internal copper wires had broken, leaving only a few strands connected and causing an intermittent open. When the signal interrupted, the ECU could not detect the evaporator had dropped below 0°C, so the compressor kept running and iced up the system. Repaired the harness and fitted a protective sleeve. Fault resolved.
Original source ↗
BYD DTC AI Analysis

Rodents chewed through wiring inside the dashboard of a Song MAX, causing a sensor open circuit.

✓
A 2018 Song MAX was parked for one week. At startup, the AC failed to cool and emitted a slight odor. The scan tool reported B2A2413 and B2A2011 (sunlight sensor faults, same harness branch). Removed the dashboard to inspect the HVAC assembly and found rodents had chewed through multiple wires in the evaporator temperature sensor and sunlight sensor harnesses above the blower motor; the evaporator temperature sensor signal wire was completely severed. Cleaned up the wiring debris, re-ran new wires from the root with corrugated tubing, replaced the damaged sensors, and performed the AC system self-learning procedure using VDS (some models require zone matching). Fault resolved.
BYD DTC AI Analysis

Qin EV300 sensor pin corrosion caused intermittent open circuit

✓
A 2017 Qin EV300 used in a coastal area had intermittent AC cooling failure. DTC B2A2413 stored as a history code, occurring mainly on cold startup. Inspection found the evaporator temperature sensor connector pins covered in green copper corrosion. The connector seal had aged, letting salt spray from sea breezes intrude and corrode the terminals. Static testing sometimes showed continuity, but driving vibration increased contact resistance, causing the ECU to misinterpret the signal as an open circuit. Cleaned the pins with WD-40 Precision Electrical Contact Cleaner, applied dielectric grease, and replaced the connector with a new sealed unit. No recurrence after one month of monitoring.
Other Qin Plus 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.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.B110BDTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.B173A1ADTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.B173BDTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
Common problems reported for Qin Plus →Qin Plus overview →
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.