Mastertemp 400 E05 error (yeah, I know... 😉 )

DockDoc

New member
Apr 19, 2021
4
Oklahoma, USA
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
two questions!

I've scoured previous threads, but haven't seen this specific question.

My heater will fire and run for 20-30 seconds SOMETIMES, and sometimes will run for several minutes at a time before failing with error E05

Through the many helpful posts in this forum, I learned to hold the "on" button for 10 seconds to get the system's take on the stack flue sensor temperature, but I also had a hand-held laser temperature sensor

While the heater was running for about 2-3 minutes, The flue sensor temp read 210 but my hand-held laser thermometer read 326

1) Can I assume that the issue is the stack flue sensor? The forums show SO many potential causes of this error!
2) I see tons of compatible SFS replacements for $20-30 on Amazon. I looked up a replacement sensor at my local Leslie's Pool place, and dang... $150! Is it worth spending that much money on the SFS?
 
Welcome to TFP.

Have you read Pentair MasterTemp Heaters - Further Reading ?

The knock off SFS works as well as the pricey Pentair ones but seems to not last as long. Buy more then one.

Test any SFS before installing. The sensor may be tested with an ohm meter (3.8 MegOhms @ 77F) If you decide to get a new SFS, check the stack flue temp when you get it back together and running to confirm that the stack flue temps are where they should be, and not too high.
 
Thanks for those resources!

Does the discrepancy in reported versus measured temperatures point to the stack flue sensor? As opposed to the other million things
 
How old is your heater?

Does the SFS have rubber insulation or braided insulation on its wires?
 
Installed in 2020. Rubber/plastic insulation

That is the time frame Pentair had bad SFS and they had the rubber insulation.

Make a warranty claim if still under warranty and you want to go through Pentair or just replace the SFS.
 
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