fablawyer

So I have had issues for 6 months that I have tried to solve. I am getting there - but not quite. So the water is 75 degrees today - so no 'cold' issues. This is what I get: Sometimes I get a 171/190 (backboard) code. It eventually clears but comes on every couple of days. Most times I am getting a 120 code. At least that doesn't stop Chlorine generation like the 171 code does. I get a general fault which clears and comes back during the day. it MAY be when the cell is reversing that it comes on but not sure. The cell is fitted for water to flow in the correct direction. It is not a cell issue. Cell is new - tried 3 different cells. It is not a backboard issue. I have tried three backboards with the same results. It is not a DC cable issue. I have tried 3 DC cables. zero phosphates in pool. salt 3400. All good. I checked all wires for breaks - all look good. So - can you think of anything else causing the fault? Would a flow sensor give me that error code? Any insights appreciated.