A blockage would typically trigger the heater pressure sensor. It could just be your heater control thermistor going bad. It's a pretty cheap replacement part. It'll be something like this: https://backyardplus.com/parts/79006-thermistor-control-thermostat-hot-spring-tiger-river-and-limelight/

However, that is not necessarily the right one for your tub.

thankyou everyone for your help - serviceman is booked!

If it's an RTD temperature sensor, increased resistance results in an increased temperature reading.

If there is a bad connection or corrosion there could be higher resistance.

I just had to replace the temperature sensor on my hot tub this week, because it was doing something similar. We did end up with a service call but it looks like the sensor was an easy replacement, and only about $70 when purchased online if we wanted to do it ourselves.

Bad control temperature sensor. Another poster listed what is likely the correct part. When they go bad due to decreased resistance the max temperature that can be displayed is 115*F.

I have a Hot Spring Limelight spa which has never caused any issues. The panel is displaying the temp as 46C but the water temp is perfect. I have tried cycling the power and nothing seems to fix it.

Any suggestions before I shell out the $$ on a serviceman please? I am wondering if there may be a blockage somewhere perhaps?

Temp reading 46C (115F) but water is 38C(101F)