Error: OH on a 2004 Sundance Altamar spa... why?

[squale]

I have a 2004 Sundance Altamar spa.  The spa is indoors and I have had it since new.  Recently I have been having some issues with the spa.  About 2 weeks ago I was using the spa and all of a sudden the 'Flo' error came up on the screen.  So I turned the power off at the breaker and then turned the tub back on and this error message went away.  It was fine for about a week, then last week I started to the get the error "OH" and the tub will actually turn off it's power.  I have the set temp at 95 degrees, this morning I went to go into the tub and the water temp was 103 degrees!!!!  but I only had it set at 95 degrees!  So this has been happening for the last couple of weeks where the OH message comes on and then the tub will turn it's power off.  I then have to go to the spa disconnect panel, turn the breaker back on and then the tub starts up again.. and shortly after the 'OH' will come back onto the display.

Also to note, I haven't cleaned the main hottub filter in about 2 months.. I am the only person who uses the spa, I use it maybe 4 times a week, 20 minutes each time and I go in naked to keep down on the soap suds.  So my filter doesn't really get that dirty.  And I run Dichlor and shock in the tub... no bromine.

any help on what to start looking at?

[squale]

okay couple more things..

took the main filter out, ran the tub for a few moments to make sure the filter wasn't causing the issue.  Still get the 'OH' message after I switch on the breaker.  I took the panels off and looked at all the tubes and the clear flow valve.. everything appears to be looking just fine and the flow valve switch seems to be working good too... plus the circulation pump runs fine and I can see the little bubbles coming out in the water from where the hot water comes in.  So I don't think I have any sort of a flow issue or clog that could be not allowing the water to pass over the heater fine.

So could there be a sensor or something that is actually putting the tub into OH mode?  The set temp is now 99 degrees, the current showed temp and what the water feels like is 101 degrees.. so it's a 2 degree difference and the 'OH' message still comes on.  So I'm a little baffled because it appears that the water is displaying it's REAL temperature just fine, and I don't see any flow issues or clogs anywhere in the clear tubing.  So what could be causing the tub to go into 'OH' ?

Thanks

[Hottubber1]

Could just be a faulty temp sensor. Part # 6600-167. It is also a relatively easy repair by the homeowner if you don't mind getting your hands dirty. They won't literally get dirty, but you know what I mean.

Hottubber1

[squale]

weird, now this morning I am having no problems, no "OH" messages, the set temp is at 99 degrees, the real temp is also 99 degrees.. so everything seems to be working fine now.  All I did was just take out the main filter in the skimmer area, clean it just like normal regular maintenance, put it back in, turn the circuit breaker back on.. and now no more messages... very strange..

[Hottubber1]

This is typical with a Sundance Spa, you never know when the "self diagnostic system" kicks in.
Hottubber1