--58 DEGREES (HOLDS AT) AND NO HIGHER-- -REPLACED TEMPERATURE SENSOR FOR NU-WAVE SPA PACK--TEMPERATURE WON'T GO ABOVE 58 DEGREES--SAME PROBLEM I HAD PRIOR TO REPLACING SENSOR. IT HAD WORKED WELL PRIOR TO THIS PROBLEM--SPA PACK IS ABOUT 6 MONTHS OLD--ANY IDEAS? ANY HELP WOULD BE GREAT--tHANKS!
MARY

is the air temperature around the tub at 58 also? It's likely that your heater is not functioning and the water is just heating to the air temperature around the tub.

I would check to make sure you have power going to the heater element, and if so, the element is bad. If not, your contactor/relay for the heater may be defective.