Dreammaker Big EZ HH error

[drcoleman11]

I have a 4 year old Dreammaker Big EZ that keeps giving me an HH error. I know  the error is for high temperatures but I can’t figure out what is causing it. I did have a blown .25 amp fuse that has been replaced, also replaced the heating element and sensors. Neither fixed the issue. Pump runs just fine at low and high speeds and brand new filter installed. Tub will work after clearing the HH error and run for one pump cycle (30ish mins) or until the temp reaches back to normal (depending on how long it sits before resetting). My thought is maybe the control board? Anyway of testing that before ordering a new one (I haven’t found anyone that will accept returns on electrical parts). Or any other thoughts of what it could be? Thanks!

[Spa Board Doctor]

Possibly restricted water flow?  Too many jets turned off?  Gate valves both fully open?  Obstruction in the front of the heater pump?  Dirty filter?

You can put it in test mode to see the temperature sensor readings in real time.  The differential between the two sensors must be four degrees or less while heating. Otherwise, heating will stop, and low flow errors will be displayed.  Higher than for degrees differential means that water is flowing too slowly through the heater manifold.