Pentair MasterTemp 400 displaying wrong temperature by 10 degrees.


New member
Nov 11, 2021
The Woodlands, Texas
I have read through most post and hope someone can assist. We have the EASYTOUCH Panel with all Pentair equipment that was installed in 2016 and has been working since. We noticed the problem last week; when you set the spa to ex: 97F, the water heats to 90F but the display on the MasterTemp panels shows 100F. We do have the limit set to 100F, so the heater is functional just the temp reading is off.

I have replaced the thermistor, high limit switch and thermal regulator and each time the results are the same. Any guidance would be appreciated.


In The Industry
Jul 14, 2014
You need to check the actual temperature of the water with a good, working thermometer (not something bought at a pool supply for $10.00). You can get a reliable, mechanical thermometer at an auto supply that is usually as accurate as necessary. After 5 years of use, I would suspect the temperature sensor of your control system, especially if it is installed in the pipe coming right out of the pump, as the problem.
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