Hi I wanted to offer an odd tip, my HotSprings 2001 Sovereign heater would only heat for 2 minutes then shut off I had replaced all major items, circ pump, heater and thermistors, heater control board. I tried running the hot tub with the 240v heater breaker off and even then it would shutoff after 2 minutes (per the IQ 2020 control board) Finally I contacted backyardplus.com to order another set of thermistors as a last shot, they helped me out by suggesting it might be the mini aux control panel (up in the tub vs the main panel on the side. They do great work and have good deals anyway they mentioned that the aux control panel might be the cause. I tested by unplugging it, the cable that looks like a phone cord plug, now the heater works great. Of course I have to replace the aux board if I want that too function again.
