Error Code: EC 53 – ODU Ambient Temperature Sensor (T4) Error

Error Code: EC 53 – ODU Ambient Temperature Sensor (T4) Error
Applies to LETO and AURA Series

What this means:
The outdoor ambient temperature sensor (T4) is giving abnormal readings or is not responding. The system relies on this sensor to measure outside temperature. If it fails, the unit may shut down as a safety precaution.

Try this first (easy fix):

1. Turn off the power to your mini split completely.

2. Wait 2 full minutes.

3. Turn the power back on and check if the error is still showing.

• If the error is gone — your system is working again.

• If the error remains — move on to the next steps.

Next steps (for technicians):

• Check the wiring between the T4 sensor and the outdoor PCB.

• Ensure everything is securely connected and not damaged.

• Measure the sensor’s resistance:

  • If the resistance is too low or too high, replace the sensor.

  • If the sensor is fine but the error persists, replace the outdoor PCB.

What you might need:

• Outdoor ambient temperature sensor (T4)

• Outdoor PCB

• Connection wires (if damaged)

Helpful tip:
In some models, the T4 sensor is part of a combined sensor along with T3 and TP. Check your unit’s wiring diagram to confirm. This error is triggered when the voltage falls below 0.06V or rises above 4.94V.

Click here to view the detailed guide. TS05-ODU