Hell there, This is my first time at this.

I recently bought a used 1998 Hercules siesta spa and the temperature on the display is 5 degrees off.

I set it for 101 and got in and it was actually at 106.

Well first I thought it was hot and at that temperature the hi limit was suppose to shut the heater down and that thought came from reading info here.

So next I checked the free floating thermostat that leisure time gave us for buying alot of stuff.

I also checked with the kids are they really sick or not digital thermo and well sure enough 2 against one.

The display is 5 degrees off and the hi limit never went and turned the heater off.

Only know problem is that the pressure switch is faulty and has been jumped{I am expecting that part tomorrow}.

Any help here as to what part I need to replace and why the heater would heat this up to 106 would be helpfull!!!!

Hi-Limit usually won't shut it off till much higher...
Probably a bad T-stat or elec temp sensor needs replacement, or has fallen out of a drywell.

++...

double check the connection where the temp sensor plugs in too... if there is any corrosion on them, they can add a slight resistance and cause a false reading to the control panel

The sensor some how came out about a quarter of an inch.

Must have been when I was messing around trying to find the leak that was caused by the pressure switch.

I have since fixed the temperature and it is off 1 degree now which is fine by me and the pressure switch has been replaced fixing all leaks.

Thank you for all of the helpful replies and this very awesome helpful place where I can find so much information.