If you get an E4, E5, E6, F1, F2, F3 error code a few things can cause this problems.
The Errors Could be Caused By…
1… Wiring Mistake or Problem
2… Bad Sensor
3… Bad PCB Board
The PCB computer board that controls a mini split is having problem seeing the correct voltage from the sensors it uses.
The wiring and many sensors need to be checked to see if they are malfunctioning.
Indoor room temperature sensor.
To troubleshoot a unit the location of the many sensors will need to be known.
This information can be found in the manual for the unit and depending on the manufacture may be available from their website.
It is also possible that the PCB board has gone bad.
If after testing all the sensors and wiring and they show good this usually points to a bad PCB board.
Another thing that can case problems is a unit wired wrong or wiring that has a short or open.
Most often these errors require a technicians and will be outside the average home DIY job.