LabWrench

I think this is a low pressure alarm, but I don't have the manual with all of the error codes here with me. When you turn the unit on, can you hear if the pump is moving water? I used to get this message because the pump would seize if it hadn't been used for a while.  So the unit would turn on and try to get the pump to move, but since it couldn't, there would be no pressure and this alarm would trigger. My solution was opening up the unit (mine was a Thermoflex 900), removing the pump, disassembling the pump head, and turning the turbine with some pliers, firmly but gently, until it could spin freely again.  Then I put it all back together and it worked fine.