OH message, after a cooldown

[swingineel]

So not to beat this to death, but I though I had some extra time to do the fix, with the weather here (minnesota) staying above 32....but it dips. So I didn't have super high hopes when I got hope from work just now, but to my surprise, the tub was running, maybe through its maintenance cycle, I don''t know, but the water wasn't icy, so I don't know if it has a freeze prevention on it, but either way it was running. OH still flashing, though.
Does that solidify any evidence?

[MaryH]

I still believe it could be a sensor. On that system the sensors may come as a set, high limit and temp sensor together. Please check the cable, Balboa will have their part number printed on it. Your topside panel, the part you sent a picture of, will not cause the spa to go into OH. Usually it will be one of the sensors, the pump not pushing enough water through the heater while it is on, or the main circuit board itself.