Mitsubishi 1102 fault

Been to this site a few times now. It has a Mitsubishi PEFY P20 VMME running from a bc box with 7 other units that heat and cool fine only this one every couple of months comes up with this fault.
The other day I found the plug o the lev half hanging out so plugged it back in and did a full factory reset.
2 months later fault appeared again.
Checked all 3 thermistors all ok.
Solenoid valves opening in bc box and reclaimed and weighed the gas all ok.
I am now thinking of changing the indoor lev and pcb.
Any thoughts on anything I could be missing as this only does it when I am not there other than I get a colder suction pipe reading at bc box 0-2 degrees c and the others are all over 10 degrees c
Thanks in advance.