Pentair MasterTemp 400 Error code E05

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Have you checked for obstructed venting? (intake and exhaust).

There's also a sensor that could be bad (stack flue sensor)

I'm not an expert, I just enjoy searching for stuff.

Here's another response that may be beneficial

"If you hold down pool on button it displays the exhaust temp. - mine was showing 80 and then flashing 40. Obviously something wrong. There is a sensor on the exhaust that looks like a bolt with 2 wires coming out of it - it's the stack flue sensor. I took it off, cleaned the terminals, screwed the sensor back in and reattached the wire terminals. After I did this - no problems.
Kenewills"
 
I unscrewed the sensor and cleaned it. Tried twice with the same results. Third time the heater worked perfectly. Tried again this morning, still working. I'll try again tomorrow, but it seems to be the issue. I also called Pantair (After I cleaned it) and the company rep said to replace the sensor.
 
I have a silly question, how did you clean the terminals? Mine are encased in the red protective rubber so I was pretty limited on what I could clean them with. My unit also flashes 80 / 40 when holding down the pool button. Cleaning it didn't help but again I was limited.
 
Cleaning might give you a few days of use but they usually fail again. The best practice is to replace with a new one. It's what is inside that is failing.
 
ps0303 said:
Cleaning might give you a few days of use but they usually fail again. The best practice is to replace with a new one. It's what is inside that is failing.
Click to expand...


The part number for the sensor is Pentair 42002-0024S.

Question: I see the non-pentair branded ones on Amazon for $22 bucks....but the pentair or sta-rite OEM ones are triple that on other websites. What quality experiences has anyone have with the OEM vs non-pentair sensors?

Thanks in advance.

Peter
 
tpn7399 said:
The part number for the sensor is Pentair 42002-0024S.

Question: I see the non-pentair branded ones on Amazon for $22 bucks....but the pentair or sta-rite OEM ones are triple that on other websites. What quality experiences has anyone have with the OEM vs non-pentair sensors?

Thanks in advance.

Peter
Click to expand...

See my reply to your new post about these parts.
 
For what it's worth...

I see more E05 errors that are due to things like a sooted exchanger(fuel delivery, venting), scaled up exchanger (water side), or a low water flow.
I see those problems a lot more than a sensor that has gone bad. I could even buy that continued high temps could eventually cause a SFS to fail. The SFS will let the heater stack temp to run up to 480 degrees before it will shut the heater down. In the case of a sooted exchanger, the stack flue temp would rise slowly over time (weeks/ months) subjecting the sensor to extended over temp conditions. The sensor may be tested with an ohm meter (3.8 MegOhms @ 77F) If you decide to get a new SFS, I would at least 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.

Normal temps should be ~290-350.

Too many times customers, even some techs, address the SYMPTOM instead of the PROBLEM. Addressing only the symptom can get expensive...
 
You are more right than wrong on your statement. Being a newbie, i opened up the panels on the MasterTemp to find a couple of mud dauber nests against the air blower vent...cleared out with a blower and VOILA....No more E05. Thanks for the tips PC!:joker:
 

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I can see this thread is old, but non-the-less, it gave me some insight into my recent E05 sighting on my Mastertemp 400 heater. Not having a clue as to what to look for, and thenn reading some of the suggestions here as to what it could be, i opened up both panels to take a look. Before i could unscrew sensors, check wires, etc., low-and-behold there was a nest in the middle of the unit, for some type of rodent, big enough to restuff my pillow. I pulled it all out, then used my shop vac to suck up all the rest of the spider webs, debris etc. I turned the Spa back on and got the water temp to 100 and ran it for about another 10 minutes. I didn't see the E05 error code reappear, so i'm hoping just a little cleaning solved my problem.
 
The heater will kick on for 30 seconds and then shut off - I replaced the stack flue sensor with pentair part #420002 - 0024S and the error still exist - the temp reads 80 and I hold it down and it doesn't change ...can't find any reason why this is not staying on and heating. could it be a bad sensor or something else?
 
steveleibs said:
The heater will kick on for 30 seconds and then shut off - I replaced the stack flue sensor with pentair part #420002 - 0024S and the error still exist - the temp reads 80 and I hold it down and it doesn't change ...can't find any reason why this is not staying on and heating. could it be a bad sensor or something else?
Click to expand...

Might be best to start a new thread on this.
 
I am having the exact same problem. Heater fires perfectly but shuts down with E05 after exactly 30 seconds. Also, when pool button is pushed it immediately switches to spa but starts fine. My heater is a little over 1 year old. Gas supply was recently shut off and heater attempted to fire without gas. Not sure if it is related.
 
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