I have a Gecko spa pack #0202-205028 that keeps throwing an HL error code. I have cleaned the filter, ran w/o a filter, checked for obstructions in heater tube and continue to get the code after water reaches the set temp. I have notice when the water reaches temp, the pump shuts off then I hear boiling type of sound. Then HL is displayed and the noise stops. I suspect that something is not triggering the heater to shut down when it reaches temp; it only shuts down the pump. does anybody have any ideas? thanks