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).
AD0 and SF1 show up when the "Off" button is held down to program the stack flue sensor.
If these show up without pressing the OFF button, it's probably a bad membrane pad with a stuck "Off" button.
SF1 is not an error code; it is a program setting.
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1. Turn the power to the heater ON.
2. Press and hold the OFF button on the membrane pad until the 3-digit display shows “Ad0” or “Ad1” (about 10 seconds).
3. Release the button and then press it momentarily.
The 3-digit display will now show either “SF0” or “SF1”.
Board must be set to “SF1” for the heater to operate with a Stack Flue Sensor installed.
4. If the display reads “SF1”, it is correctly set.
If it reads “SF0”, use the arrow buttons on the membrane pad to set it to read “SF1”.
5. Momentarily press the “OFF” button to exit the program.
https://www.pentair.com/content/dam...ift-asset-library/pool-spa/S381(11-16-04).pdf
www.troublefreepool.com