Intex saltwater system issues

We bought a complete intex system last year,16'×48" round above ground pool,sand filter and saltwater system.It ran perfectly all year.Drained below intake for Winter and refilled with fresh town water this spring.
Again everything ran fine for the first couple of weeks but recently constant error codes which shutdown the system.It will run fine one day,shutdown the next due to low water flow,low salt level,high salt but then run fine the next day!.
P.H tests between 7.2 and 7.8,Alkaline level is good,even the copper level is within range at 0.3,so any ideas as to what is going on?,i should add it holds 5000 gallons and that I've changed the sand,soaked the electrodes in white vinegar and checked the cell.My main concern is that if it is due to high salt,is there anything we can do apart from draining it.