Jacuzzi 330, temperature incorrect, OH comes on

I have a 2003 Jacuzzie 330 spa. I set it for 98 degress because when the digital temperature reads 98, the actual water temperature is 101 (floating thermometer). I could deal with this, by just adjusting setting, but when the tub heats to a reading of 98, the OH light comes on.

If I reset the external GFI, the OH light goes off, but comes on again later.

Thanks for any help. Jim

Usually when the temperature doesn't match what the topside display is saying it is the issue is with the temperature sensor.