C Whim

I have a Bullfrog spa with a Balboa heater. (I think an M7) I get the dr code, but there is plenty of action from both pumps on high and low settings, so i don't think it's an airlock. Also the temperature appears to think the water is 103-107 degrees and bounces around, yet the water is straight out of the hose and maybe 65 degrees. I've already tried replacing both of the sensors. (I have also removed the filters to ensure not a flow issue) Any suggestions to help diagnose?