replacing the thermostat and high limit thermistors is pretty easy and inexpensive if you want to try and avoid a service call. the 2002 sovereign has the heater circuit board in its control box that has caused numerous heating issues. i don't recall ever hearing it causing an overheat problem. the thermistors seem the most logical cause to me, but wait to hear some other members chime in, as i am way closer to the grasshopper as opposed to the number of spa masters roaming this board during the work week.
