The “SY EF” stands for “evaporator fan”, but that is not always the case. Sometimes, a reset clears the issue.
Switch off and unplug your fridge for 3-5 minutes. Plug it back in, wait for a few minutes and switch it on. Press the default button and see if the code has gone. Do not plug it into an outlet featuring a reset button. If it is plugged into this type of outlet, plug it into one without the reset function and see if the system resets itself automatically.
There may be poor wiring between the control board and evaporator fan. Check the 12VDC located between the brown and red wires and variant voltage between the brown and yellow wires. If no issue is detected, repair or replace the evaporator fan or control board.