RDspaguy

It's a stuck temp button or short on the circuit.

Ok. The mystery is that it corrects for a while then returns. The temp sensor is accurate and it shows the tub gradually overheating as it continues to run the pump, or it shows a normal temp then triggers an overheat error randomly? I'm not familiar with that system, @CanadianSpaTech is the local gecko expert. Maybe he has some insight.

Post pics of equipment area and circuit board.

Not the same thing. You can lose a leg on the breaker and still read 120v to ground or neutral on both wires. Test for 240v red to black. A continuity test must be done with the fuses out. If installed, test voltage. The spa will run automated functions with the topside disconnected. If it did not then the topside is not the problem, the circuit board or breaker is. Replace fuses. Verify 240v to spa. Remove board a check the back for damage.

Yep. They usually come with a factory jumper on the board.

🫡

If it has a pressure switch jumper it. Most IQ packs don't. They are prone to failure and have been eliminated by many control manfs by using flow switches or sensor protection. The fact it has no pressure switch used to be a selling point for HS. They were first with input/output sensors, the very system later adopted by balboa, the leading spa control manf in history, for their M7 technology. It figures, the one single solitary time I don't ask for pics and it's an oddball.🙄

How long after power reset until it shows the error? A few seconds, a minute, several minutes? It is most likely a bad sensor. Replace both at the same time. They should be noted on the wiring diagram, just track the wires as needed.

Check with your dealer, but I'm inclined to say you cannot. It depends on how it's plumbed.

You need to determine if it is switching off at the board or not. If it has power to the pump when the pump is not running it's a pump issue.

The red jumper wire going to a terminal labelled "jet 1 & 2" determines voltage to the pumps. Verify correct voltage. Verify correct pump wiring, as the red pump wire goes to a terminal labelled black. This does not mean it's wrong, but it may be depending on where the other end of that wire is.

Most likely the heater is running without flow or the sensor is touching the element. Remove filter. Check heater pump, which is often a different pump than the jets, for flow. Check to verify power is turning off to the heater as a stuck relay will cause it to do as you describe as soon as power is turned on.

From your description it is likely a flow or sensor issue. Is the tub actually getting too hot overall? Bold statement. How was this determined? Remove circ filter (the closest to the pumps) and test. Check circ pump for obstructions. Check circ for loud or hot operation (you should barely hear it and should not jerk your hand away when you touch it). Test thermistors (unlikely but I'd do it anyway).

The white wire determines component voltage anx connects at the main power terminal block for 240v or 120v. Just follow the other white wires to find them.

The heater should not be effected by a leak unless electrical components are wet.