Single Status Update
I have a similar problem - my coleman horizon 400 spa heater not turning off. I set temp to 80 but heater heats water until high temp sensor shuts down spa (usually around 110 degrees) sn1 and after a while after cooling I get the OH code and than I can restart the spa. But, the heater seems to continue to operate. I hear a hum from the heater area as if the heater is always on. I shut down the whole spa over night to cool. When I turned on the spa again, the heater got hot to touch pretty quickly - the water temp this morn was 104 degrees at startup, the hight temp sensor triggered again. any idea. hope you understand.