Stay Rite Max E Therm 400 E 01 error code

Mar 5, 2019
Tallahassee, FL
Hi All,
Thank you in advance for your help.
In the fall we moved into a house with a 2016 installed Sta Rite max E therm 400 gas heater. It worked fine initially, but the would shut down intermittently and the service heater lite would come on. Turing power of and back on would usually get it going again. Last week, it threw a AFS light. I checked the tubing and blew into tube confirming function with voltmeter. I’ve had no further AFS codes. But then it began to have erratic temp readings jumping around. If the temp jumped below what set temp we had previously put in, the blower would come on and subsequently infinite, but the temp would then jump up and it would shut down.(I guess appropriately for what it thoughtbthe temp was)
I replaced the Thermistor thinking that was the issue( old thermistor had some pitting and corrosion) Immediately after I replaced it, the unit clicked and threw an E 01 code on the membrane read out. It would then not startup, or show anything except the E01. I checked all connections.... good.
The under side of the control board red LED 7 and 11 are lit. I powered down, turned off breaker.... then powered back up .... got the usual 126 then R13, then click and E01.
From what I’ve read , E01 is open circuit to thermistor.
The wiring looks good and the thermistor is new.
Could it be the control board?
I stopped by the pool shop and the guy there said he would just start replacing parts if he came out....


TFP Expert
Mar 2, 2011
If the wiring and thermistor are good, then I would suspect that the control board is bad.


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Do you have the old thermistor to reinstall as a test?
Mar 5, 2019
Tallahassee, FL
I turned on the heater this afternoon....
Startup seemed normal. Blower came on and igniter fires up.... readout read 62 or so which is likely accurate.... then I set temp to 80 which seemed to hold ......
Got home a few hours later.... blower and burner still running.... but readout said 326 or so. I turn it off and back on and reading temp was 72..... again, probably accurate....
Still wonder if control board bad?


TFP Expert
Mar 2, 2011
The 326 readout was probably the stack flue sensor temperature. You get that by pressing the on button for about 10 seconds. So, that might indicate a sticking "On" button.

The E01 is open water temperature sensor. If the water temperature sensor and the wiring are good, that would indicate a bad control board.

I would start by replacing the control board.

You might also need the membrane pad if that looks bad, but I would try the control board first.

I think that the following are the LEDs:

1.....PS (Pressure Switch)
2.....HLS (High Limit Switch)
3.....SFS (Stack Flue Sensor)
4.....AFS (Air Flow Switch)
5.....AGS (Automatic Gas Shutoff).
6.....Service System
9.....Pool On
10...Spa On
11...Service Heater.

I think that led #7 was supposed to be thermistor, but it doesn't seem to be on any boards.

If you have a board that has the #7 led, can you post a picture of it?
Last edited:
Mar 5, 2019
Tallahassee, FL
Second update:
I fired it up yest and it has run correctly last nite and today..... no further E01 codes.
Any chance the board took some time to reset and clear the code?
I replaced an o2 sensor on my truck and it took a few days before the check engine life went off?
I will hold on replacing the control board for time being.....


TFP Expert
Mar 2, 2011
As long as it's working.

I suspect that the board is probably going bad due to the multiple erratic issues.

Let us know if it has further problems.
Mar 5, 2019
Tallahassee, FL
Quick Follow Up:
As mentioned above, after changing thermister and letting the pool pump power up and cycle a few times, the heater started working properly. However, now, it will switch modes from pool to spa on its own. Also, if I turn it off, (heater off button), the next time the pump cuts on the heater starts heating again. I does seem to cycle off when it heats to the set temp, but it always switches back to spa mode.
Given the E01 codes from before, and now the mode switching and not staying off after its turned off, does this sound like the membrane of the board?

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