Yes, I can switch back between pool and spa. It shows the different temps set for each.Lately Ive noticed if its an E05 code it isnt the stack flu but the touchpad is faulty. When the heater is on either pool or spa can you switch between the two by pressing pool on then spa on or vice versa? if you cant your problem is the membrane touchpad.
I've tried two new Flue stack sensors. Wiring looks good....no sign of rodent infestation. Heater worked a month ago...When you pressed the pool button previously to get the stack temperature and got 80, that's an indication of a bad sensor or wiring. Replace the sensor and check the wiring then fire the heater and recheck the stack temperature.
I pulled it and it looks clean to me....Pull the Thermo-regulator and inspect for corrosion. Even a little will cause problems (I realize you replaced it last season, however, they can get corroded up in a month). Your looking for white or GREEN corrosion.
Note: E05 and E06 are more or less the same thing... Problem with SFS.
You can get an E05(open sensor) if a rat chews through the wire(s).
An E06 is a shorted sensor, or if the board thinks it is a switch, and not a thermistor (didn't get programmed when it was installed).
Heater fires and runs for 20-30 seconds then shuts off with E05 error.Does the heater fire?
What happens when you press the pool button?
I know this is probably review, but are you pressing and holding the button down for at least ten seconds?