Mastertemp 400 E05 error

wpbucher

LifeTime Supporter
Feb 7, 2012
143
South-Central Pennsylvania
Hi,

Heater turns on for 30 seconds then throws an E05. Based on previous threads, I replaced the stack flew sensor....still throwing E05 code. Inside of unit looks clean. No signs of rodents or insects. Heater worked about a month ago....

Any ideas? Thanks for your help.

Picture of circuit board:MasterTempE05Code.jpg
 

Pool Clown

In The Industry
Sep 5, 2008
1,978
Silicon Valley, CA
Turn the heater on. The fan will come on for about 30 seconds, then you will hear a click, and the heater should fire. At that moment, which ever thermostat you are using (pool or spa) hold that button down for ~10 seconds. Display should change from water temp to exhaust temp. Normal temps should be in the range of 290-350. 350-500 is considered high and you should look for a...

1) Sooted exchanger(external) due to improper gas pressure or lack of proper venting. either supply of fresh air or exhaust, or both. Heater is being starved of air and the resulting air/fuel mix is too rich (fat).
2) Calcified exchanger (internal) due to improper water chemistry. Note: Not necessarily right now, but at some point, and for a while. This wont happen over night.
3) Flow or velocity issue. Water is moving too slowly through the exchanger, gathering or absorbing too much heat, and is not carrying it away quickly enough to keep the heater at a workable temp. In this case, you may have a valve closed down, but not fully closed, or may be wanting to save a little more money on your electricity bill, so you turned down your VS pump as low as you can get away with. You will need to turn it back up to correct this !
 

Elheffy22

Member
May 11, 2016
5
Rochester NY
Lately Ive noticed if its an E05 code it isnt the stack flu but the touchpad is faulty. When the heater is on either pool or spa can you switch between the two by pressing pool on then spa on or vice versa? if you cant your problem is the membrane touchpad.
 

wpbucher

LifeTime Supporter
Feb 7, 2012
143
South-Central Pennsylvania
When I turned on the heater, it read "82" for water temp. After it clicked on, I pressed the button and reading changed to "80" and stayed there. So I never got a flue temp. I used my multi-meter to check resistance of new SFS. It showed "open loop"....so I think the new SFS is kaput. Returning to Amazon....it said it was Pentair...but it wasn't . I've ordered a Pentair SFS....I'll let you know how I make out.

I checked the new SFS because everything else looked clean.

IMG_2242.jpg
IMG_2243.jpg
IMG_2245.JPG
IMG_2246.jpg
IMG_2247.jpg
 

JamesW

TFP Expert
Mar 2, 2011
16,380
After you turn on the heater set to Pool, press and hold the pool button until the stack temperature reading appears.

Did you install the new SFS?

What was the new part number?

Was it a StaRite part?

The SFS for the Starite maxetherm is the same part as the Sfs for the pentair mastertemp.

Is the heater a 400hd model?

The stack flue sensor measures in the megaohm range. If your meter isn't good in that range, you might get a false open line reading.

If the part was new, it was probably ok.

E06 is a bad sfs.

E05 is usually overheating. That's probably what's going on.

The 400hd model is somewhat prone to overheating, partly because it's less efficient and more heat is wasted, so the exhaust runs hotter than the non hd model.
 

wpbucher

LifeTime Supporter
Feb 7, 2012
143
South-Central Pennsylvania
Lately Ive noticed if its an E05 code it isnt the stack flu but the touchpad is faulty. When the heater is on either pool or spa can you switch between the two by pressing pool on then spa on or vice versa? if you cant your problem is the membrane touchpad.
Yes, I can switch back between pool and spa. It shows the different temps set for each.
 

wpbucher

LifeTime Supporter
Feb 7, 2012
143
South-Central Pennsylvania
New SFS shows up. Looks like the one I just sent back.

Here is the packaging:
SFS.jpg

Previous post stated ohms....not megaohms...so my multi-meter is not equipped for that.


I don't see "HD" anywhere on the heater.
Here is the label from my heater.
MasterTemp.JPG

I read some old threads and checked to ensure my heater was set to "SF1" vs "SF0". It was at "SF1".

Heater installed in 2013. Never had this issue.
Last year (or maybe the year before) the heater would shut off at 87F. I replace the thermo regulator.

If have VF pump. Always ran heater at 22gpm. I increased to 30gpm...still get the E05.

Any other ideas? Old post had "control board" replacement as a possible solution......say it ain't so!!!

Thanks for your help.

- - - Updated - - -

Oh yea...one more thing. I'm very careful with the pool chemistry. Vinyl liner pool....keep PH at 7.4-7.5.
On my second SWCG...but everytime I have checked them there was no calcium buildup.
 

JamesW

TFP Expert
Mar 2, 2011
16,380
That's the right thermistor. Start the heater in Pool mode and once it fires, press the Pool button until the stack temperature shows up.
 

Pool Clown

In The Industry
Sep 5, 2008
1,978
Silicon Valley, CA
Pull the Thermo-regulator and inspect for corrosion. Even a little will cause problems (I realize you replaced it last season, however, they can get corroded up in a month). Your looking for white or GREEN corrosion.

Note: E05 and E06 are more or less the same thing... Problem with SFS.

You can get an E05(open sensor) if a rat chews through the wire(s).
An E06 is a shorted sensor, or if the board thinks it is a switch, and not a thermistor (didn't get programmed when it was installed).
 

JamesW

TFP Expert
Mar 2, 2011
16,380
When you pressed the pool button previously to get the stack temperature and got 80, that's an indication of a bad sensor or wiring. Replace the sensor and check the wiring then fire the heater and recheck the stack temperature.
 

wpbucher

LifeTime Supporter
Feb 7, 2012
143
South-Central Pennsylvania
When you pressed the pool button previously to get the stack temperature and got 80, that's an indication of a bad sensor or wiring. Replace the sensor and check the wiring then fire the heater and recheck the stack temperature.
I've tried two new Flue stack sensors. Wiring looks good....no sign of rodent infestation. Heater worked a month ago...
 

wpbucher

LifeTime Supporter
Feb 7, 2012
143
South-Central Pennsylvania
Pull the Thermo-regulator and inspect for corrosion. Even a little will cause problems (I realize you replaced it last season, however, they can get corroded up in a month). Your looking for white or GREEN corrosion.

Note: E05 and E06 are more or less the same thing... Problem with SFS.

You can get an E05(open sensor) if a rat chews through the wire(s).
An E06 is a shorted sensor, or if the board thinks it is a switch, and not a thermistor (didn't get programmed when it was installed).
I pulled it and it looks clean to me....
ThermoCoupler_20180822.JPG

- - - Updated - - -

Does the heater fire?

What happens when you press the pool button?
Heater fires and runs for 20-30 seconds then shuts off with E05 error.
When I press the pool button when the heater ignites, the water temp reader changes to "80".
 

JamesW

TFP Expert
Mar 2, 2011
16,380
If the wiring going to the SFS is all good, I think that that leaves the board as the likely problem.

Part number 42002-0007S.
 

JamesW

TFP Expert
Mar 2, 2011
16,380