We've had this happen several times now and up until today it's only happened when the booster pump was running. We get the PCB error and the no flow, check salt, high salt, and inspect cell light are all on as is the power LED. Turn power off for a minute or two and it may run fine for the next 8 hours again. I just replaced the flow switch and rinsed the cell which looked quite clean fwiw. I haven't received my Taylor salt test yet, but the instantaneous salinity is within a 100 ppm of what the pool shop is giving us if that matters.