MasterTemp 250 E05


New member
Apr 25, 2019
My unit runs for around 40 mins, raises the pools temperature, seems to be working fine and then catches an E05 error. I've replaced the flue stack sensor, and get the same behavior. Once it gets the E05 I can restart it, and it will run for a short period of time and I'll get another E05 error. I've tried once I get the E05 error to hold down the spa or the pool button to see if I can get output of some other code, but that doesn't seem to work for me. I have to press the off button and then it restarts. A couple of other items I'll note because in case they might help diagnose the issue. From time to time the unit won't fire. I have a small paver brick I use to tap on the gas manifold and that always does the trick. Also, from time to time, the unit will attempt to re fire, and I hear the click, but it seems to go out immediately and will click again 2-3 times, it sounds like each time the click occurs gas in the system ignites and it causes the unit to shake a bit. When this happens it only takes about 3-6 seconds until the unit is running just fine, but it doesn't seem like it should run that way.

Thank you for any help.


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Welcome to TFP.

Read the section on E05 errors in Pentair MasterTemp Heaters - Further Reading

E05 can be caused by low water flow caused by a dirty filter or algae clogging your filter,

What filter do you have?

What is the filter clean PSI?

What is the filter PSI now?

Please create your signature with details of your pool and equipment so we can give you more specific advise.


New member
Apr 25, 2019
Thank you very much, I'll review that page and check things out and report back. I've updated my signature.


New member
Apr 25, 2019
I asked the kids to run across and get me the numbers. We have 10psi on the 6 month old gauge, no reason to think it is broken, but maybe. Also, the flue temp reads between 250 and 310 the couple times we have checked it. Interestingly, we changed the flue sensor last night around 7pm. Two hours later at around 9pm, the pool was 2 degrees warmer (from 56 to 58 degress), from my experience we get around 3 degrees an hour when the air temp is in the 40s, so could possibly have been running over an hour before the E05 error hit. At that time (9pm) I turned the heater off and then back on. When the kids just went over the heater was still running from last night at 9pm. Pool is at the set temp of 99 degress.


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