[Chinese Hot Tub Temperature Problem!]

Yes, filter is new and the pumps are working. The heater was renewed last summer too!

[Chinese Hot Tub Temperature Problem!]

Hi guys, this is my first post, but I wonder if anybody could help me. I have a Chines hot tub. When I switched it on a few weeks ago the temperature reading said 40 degrees C, but the water was actually 16 degrees C. I renewed the temperature sensor but the problem remained. I have today replaced the PCB with a new one (as I was told it could only be one of these two things!). Now I have an "FF" error code. Anybody have any ideas?

Thanks in advance.

Dave