My Pentair Mastertemp 400 runs for a few minutes then goes to E01 error which is Thermister error, and then service heater light comes on. I replaced the thermistor but the problem continues. Spoke to Pentair customer service and they said most likely control board is bad. So I ordered an new control board from an online pool supply company and after installation I get nothing, no LED's etc. Seems strange but could I have been shipped a new (defective) in the box board? By the way electronic boards are not returnable.