Error Code: EC 56 – Indoor Coil Outlet Temperature Sensor (T2B) Error (Multi-zone)

Error Code: EC 56 – Indoor Coil Outlet Temperature Sensor (T2B) Error (Multi-zone)

What this means:
This error appears when the T2B sensor, used in multi-zone systems to monitor the indoor coil outlet temperature, is either disconnected, shorted, or producing an out-of-range signal. If the sensor voltage is below 0.06V or above 4.94V, the system triggers EC 56 and shuts downTS23.

Try this first (quick reset):

1. Turn off the power to the unit.

2. Wait 2 full minutes.

3. Turn the unit back on and check if the error disappears.

• If the error clears — the issue may have been temporary.

• If the error remains — continue with sensor diagnostics.

Next steps (for technicians):

1. Check the sensor wiring:

   • Ensure the T2B sensor is properly connected to the indoor PCB.

   • Repair or replace any loose or damaged connection wires.

2. Measure the resistance of the T2B sensor:

   • If resistance is out of range → replace the T2B sensor.

   • If resistance is normal but the error persists → replace the indoor PCB.

What you might need:

• T2B temperature sensor (coil outlet, multi-zone)

• Indoor PCB

• Connection wires

Helpful tip:
This sensor is specific to multi-zone indoor units. Single-zone models do not use T2B and will not display this error.

Click here to view the detailed guide.TS23