Mastertemp 400 E05 error

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J

jlamb5990

Bronze Supporter
Jan 22, 2022
213
South Louisiana
Pool Size
10000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Pool is just coming up on 1 year and the heater worked perfect all through last winter and heading into this one. Went to fire it up Monday and it kept killing after about 5 min and progressively got shorter on the time until shutdown. Was getting the E05 error. I ran it and checked the SFS temp during startup and it steadily climbs to about 250 then all the sudden drops to 40 and then shuts off about 10 seconds after that. I’ve read it’s probably a bad sfs sensor and have one arriving tomorrow. Just curious if there is anything else to check in the meantime.

I’ve also made sure I have 40 gpm min running through it and also opened it up entirely to make sure there are no nests or environmental blockages; all clear. Have some people coming over this weekend so really want to make sure I’m up and running by Saturday.
 

E05 error on Pentair Master Temp 400

Brand new heater throwing an E05 error. Had Pentair out about a month ago and they changed out SFS and it still gave them the error. They recommended having gas meter upgrade, so I did that last week and still get the error. I’ve adjusted flow rate of water and still E05. Pool is 4 months old...
www.troublefreepool.com www.troublefreepool.com
 
If the SFS reads 80, then flashes to 40, then back to 80, then the 80/40 reading and E05 indicate that the board is not getting a reading from the sensor.

Try reseating the connectors on the SFS.

Otherwise it's a bad sensor or damaged wires.

If the sensor and wiring are good, the board is probably bad.

Disconnect the sensor and check continuity across its terminals.

Resistance should be 3.5-4.0 megaohms.
 
ajw22 said:
How did you make sure you have 40 GPM?

What filter do you have? None is listed in your signature.

More likely a dirty filter then a bad SFS.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com www.troublefreepool.com
Click to expand...
Filter was just cleaned this yesterday since I thought that could be an issue too. Cleaned off with a hose and then an overnight soak in cleaning solution. Still got E05 after cleaning. It’s a 4 cartridge pentair. For pump pressure I used screenlogic and put the pump pressure and 45gpm and verified it was running at such through the screenlogic app.
 
ajw22 said:
If the SFS reads 80, then flashes to 40, then back to 80, then the 80/40 reading and E05 indicate that the board is not getting a reading from the sensor.

Try reseating the connectors on the SFS.

Otherwise it's a bad sensor or damaged wires.

If the sensor and wiring are good, the board is probably bad.

Disconnect the sensor and check continuity across its terminals.

Resistance should be 3.5-4.0 megaohms.
Click to expand...
Yea I’m not getting the 80/40 ever. Just drops to 40 and then shuts off about 10 seconds later. Also tried reseating the connectors at both the sfs and the circuit board.
 
jlamb5990 said:
r. For pump pressure I used screenlogic and put the pump pressure and 45gpm and verified it was running at such through the screenlogic app.
Click to expand...

What RPM was that?

What was the PSI on your filter?
 
jlamb5990 said:
Pool is just coming up on 1 year and the heater worked perfect all through last winter and heading into this one. Went to fire it up Monday and it kept killing after about 5 min and progressively got shorter on the time until shutdown. Was getting the E05 error. I ran it and checked the SFS temp during startup and it steadily climbs to about 250 then all the sudden drops to 40 and then shuts off about 10 seconds after that. I’ve read it’s probably a bad sfs sensor and have one arriving tomorrow. Just curious if there is anything else to check in the meantime.

I’ve also made sure I have 40 gpm min running through it and also opened it up entirely to make sure there are no nests or environmental blockages; all clear. Have some people coming over this weekend so really want to make sure I’m up and running by Saturday.
Click to expand...
Don't know what is happening with those sensors. I have replaced 6 in the last three months or so. One on a heater that was installed just over a year ago, others on heaters about 2 - 3 years old, one 10+ years old. The generic ones found on Amazon for about $15.00 seem to work as well as OEM. Been using them for several years.
 
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1poolman1 said:
Don't know what is happening with those sensors. I have replaced 6 in the last three months or so. One on a heater that was installed just over a year ago, others on heaters about 2 - 3 years old, one 10+ years old. The generic ones found on Amazon for about $15.00 seem to work as well as OEM. Been using them for several years.
Click to expand...
That’s what I ended up ordering. I think it was $18. Pool shop wanted $125 for it. Based on everything above, you think it’s a safe bet that’s what the issue is?
 
jlamb5990 said:
That’s what I ended up ordering. I think it was $18. Pool shop wanted $125 for it. Based on everything above, you think it’s a safe bet that’s what the issue is?
Click to expand...
With readings like you are seeing, a sudden drop to 40 (which seems to be the common symptom), it is the least expensive option. Yeah, OEM is crazy high-priced. The other is the board itself, not inexpensive. If you can test in the mega-ohm range, you can verify the old one is bad, as ajw22 pointed out. But, for the time it takes to open that case just to get to the sensor to test, and for the little that was spent on the new one, I just replace them, its quicker than getting out the meter. I keep a few generics on my truck now and have never had a problem with them. So far, that has always solved the issue.

Pentair tech support suggests testing their new ones before installation as well, apparently aware of an issue. The last support person I spoke with just three weeks ago recommended buying at least two of theirs and testing to be sure as he had been hearing reports of their replacements being bad as well.
 
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ajw22 said:
Resistance should be 3.5-4.0 megaohms.
Click to expand...
Even if the resistance tests as good, the sensor might still be bad.

The problem might not show up until the sensor heats up.

You would need to be able to find the thermistor chart and compare the readings at several temperatures including up to about 500 degrees.

It would probably be worthwhile to keep an extra available to use as needed.

Most likely Pentair is buying cheaper parts to save money or the sensor manufacturer is making the parts cheaper and reducing the quality.
 
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Good news and even better news to report. Good news is the spare sfs came in today (a day early!). Better news is that it fixed the issue. Took all of 2 min to swap the sensors and we are back in business. Thanks for all the help everyone. Weekend party is saved!
 
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