AU
B2A2413

DTC B2A2413 indicates the air conditioning control unit (AC ECU) detects an open circuit in the evaporator temperature sensor circuit — Atto 8

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 Atto 8 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 and damage, causing poor or no cooling and possible battery thermal management issues. Common causes include a failed sensor or a loose/damaged 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 — Atto 8
  • 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 package seal failure allows moisture ingress, resulting in 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 connector) on the HVAC assembly inside the front passenger-side dashboard to loosen, the locking tab to break, or a terminal to back out, resulting in poor contact.
  • 3Physical wiring harness damage: Metal edges cut the wiring harness inside the dashboard during assembly or repair, or rodents chew through the signal wire (quiet EV motor compartments attract rodents to chew wiring harnesses).
  • 4Pin corrosion: Operating in coastal or high-humidity areas degrades the sensor plug sealing ring. Moisture intrusion 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 prevents correct recognition of the sensor signal (determine this only after ruling out the first four items).
What To Do
  • 1
    Connect the VDS2000/Launch X431 diagnostic tool. Access the air conditioning system to read fault codes. Confirm B2A2413 is a Current DTC. Record the Freeze Frame data to observe the ambient temperature and system status when the fault occurred.
  • 2
    Remove the front passenger-side glovebox or lower trim panel, locate the evaporator temperature sensor (positioned between the fins on the right side of the evaporator core, usually 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 and measure the resistance between the two sensor terminals using a multimeter. At an ambient temperature of 25°C, the normal value is approximately 2.0-2.5kΩ (refer to the temperature-resistance curve table in the workshop manual). If the multimeter displays OL (open circuit) or the resistance significantly exceeds the nominal value, replace the sensor assembly.
  • 4
    If the sensor resistance is normal, measure the wiring harness connector. Turn the ignition switch ON and measure the voltage between the signal wire and ground; it should be the 5V reference voltage. Turn the ignition switch OFF and measure continuity from the sensor connector to the corresponding air conditioning controller pin. The resistance should be less than 1Ω. If there is no continuity, inspect the wiring harness in sections to locate the open circuit.
  • 5
    Check sensor connector pins for oxidation, spreading, or bending. If necessary, clean the pins with electrical contact cleaner and restore pin tension. Apply conductive grease, reconnect the plug, and fully engage the locking tab.
  • 6
    If the wiring harness and sensor are normal, remove the air conditioning controller. Inspect the corresponding controller terminals (usually specific pins in the B23 or B24 connector) for dry 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. Monitor the data stream to verify the evaporator temperature gradually drops from ambient temperature to within 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 Atto 8 Fault Codes
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.B110A02DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.B110B07This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.B173CDTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
Common problems reported for Atto 8 →Atto 8 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.