SOLVED! Pentair MasterTemp 250 Error E01 - 126 -Not the Thermistor...

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mchartra

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Oct 8, 2013
19
Canton MI
Pool Size
20500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Hey gang. I am fearing that my control board has gone bad and before I take the plunge into an expensive replacement, I wanted to get some advice from smarter people than me on what else I could troubleshoot.

-Would anyone by chance have a schematic for the board that shows logic flow?
-I already have the Pentair Troubleshooting flow chart but it's not yielding anything but "replace board".

I should preface this with the fact that back in May my heat exchanger died. After 4 diffferent orders for parts that were cancelled, I finally lucked out on a wait list and received a new kit 474059. Spent last weekend cleaning and replacing the coil along with all of the corresponding components in the kit.

I don't believe this error is related to the coil (gaskets, ignitor, insluation, etc..) All parts in kit (except manifold by-pass valve kit) were installed.

So. I had a new Thermistor that I bought last Fall because I can recall the E01 coming up before we winterized and figured I would attack the problem in the Spring.

-Swapped Thermistors -still the same error.
-Took my multimeter out and both thermistors test OK - new one at 11K Ohms, installed one at 9.4K Ohms.
-Tested the wires from the thermistor to the board for continuity -checks out OK.

Note: The Temp Fault resistor on the board has a brown spot on it (possible burn) but that resistor which is marked as 2K Ohms also checks out- reading just below 2K.... See PIC
-- Could it be that even if the resistor measures the right resistance, it could still be faulty?
--Is this resistor related to the Thermistor or the High Limit switch?

On boot-up, I get "Service Heater" light on panel w E01 and then the display shows 126 after the self-checks.

Looking at the LEDs on the board, I have 2 that are Lit:
-LED 7 -which is at the power input -that must be normal.
-LED 11 - which is not marked but it's lit. Is this normal operation?
-NONE of the other circuit LEDs are lit: PS/HLS/AFS/AGS/SFS.

I don't see any other burn marks or other signs on the board that might indicate a blown components. See PIC

Is there anything else I can check or troubleshoot board or system wise before I buy a new board?

Thanks in advance!! Marc
 

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  • The "E01" code is an indication of an open or bad water temperature sensor that is also called the thermistor on the parts diagram.
126 usually means a shorted water temperature sensor (Less than 3,312 ohms).

If you have replaced the thermistor, then the board is probably bad.
 
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You can put a 10k resistor in place of the thermistor to see if the temperature reads 77 degrees.

If not, the board is bad.

Note: Do NOT run the heater like this without a good thermistor as it could overheat.

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Pool Heater Issue

I have a Pentair Matertemp heater. The problem is the heater is sensing a higher temp than the actual water temp is. I have replaced the thermister 2 times and still have the same issue. When I try to heat my hot tub I can only get the heat up to about 98 because the heater thinks it is 104...
www.troublefreepool.com www.troublefreepool.com
 
Gang. I am having the most frustrating time with diagnosing an E01 /126 issue. I've tried different thermistors and a test w a 10K ohm resistor. The thermistor OHM values check out and using a 10K ohm resistor as an alternative to the thermistor still yields the same result - E01/126. This definitely looks like a bad board.

I checked the thermistor wires leading to the board for continuity and they both check out.

My heater contains board #42002-0007 Rev C. R.13

I borrowed another board to test. This one #42002-0007S Rev L. R14. It's got an updated display and revised board chip layout.

Unfortunately, it came up with the same E01/126 error. The owner - fellow forum member (thank you!) said the condition of the board was unknown as he decided to replace his heater after he bought the board so he could not confirm it was good -though relatively new.

I would be surprised if I had 2 bad boards in a row but I guess I'll have to get a 3rd one in.

Q: Should I buy the latest board which is Pentair 461105 - which comes with a new keypad membrane? OR Should I try and find the same version as mine?

Are all of these boards plug/play? Or is there an update to the EasyTouch controller that also needs to be done? In other words, does my EasyTouch + Screenlogic protocol adapter even know that the heater control board is different?

I am already $800 out of pocket, having just replaced the heat exchanger. Had I known I had another costly issue, I would have just bought a replacement heater.. Argh..

I haven't tested the power supply going into the board. Is it possible that this might be my issue? Still wondering -it's possible, but not likely that 2 boards would be bad and the wiring and thermistors check out...

Assume its would have nothing to do with the high limit sensor? I would assume if it was bad, I'd have a different error code and an LED lit on the board for the HLS. Both LEDs: 7 (Thermistor) and 11 (Service Heater are lit) on both boards.
 
mchartra said:
Gang. I am having the most frustrating time with diagnosing an E01 /126 issue.
Click to expand...

I understand the E01 error which displays on the heater panel.

Where is the 126 from?

mchartra said:
Q: Should I buy the latest board which is Pentair 461105 - which comes with a new keypad membrane? OR Should I try and find the same version as mine?

Are all of these boards plug/play? Or is there an update to the EasyTouch controller that also needs to be done? In other words, does my EasyTouch + Screenlogic protocol adapter even know that the heater control board is different?
Click to expand...

I think retailers have the new board in stock. You may find someone with the obsolete board but that is a long shot.

The old control board has been replaced by the new Connected Heater control board p/n 461105. The new Control Board Kit 461105 comes with "6 button" membrane keypad. When replacing a control board on an older heater that has a 5 button keypad, you will also need to update the heater to have the 6 button keypad.

See the Pentair MasterTemp & StaRite Max E Therm : Parts Matrix for “Connected Heater” Update May 2021.

mchartra said:
I haven't tested the power supply going into the board. Is it possible that this might be my issue?
Click to expand...

I doubt it.

mchartra said:
Still wondering -it's possible, but not likely that 2 boards would be bad and the wiring and thermistors check out...
Click to expand...

Anything is possible.

I would go back to using the 10K resistor while diagnosing the problem. Try and connect the 10K resistor directly to the board thermistor connection.


mchartra said:
Assume its would have nothing to do with the high limit sensor? I would assume if it was bad, I'd have a different error code and an LED lit on the board for the HLS. Both LEDs: 7 (Thermistor) and 11 (Service Heater are lit) on both boards.
Click to expand...

You should.

Did you put your ohmeter on the HLS sensor and see that it is closed?

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
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ajw22: Thanks for the breakdown and fantastic feedback!! The control panel comes up with E01 after it goes through the self test and then the temp shows 126. It's very inconsistent though -sometimes the E01 stays on the panel, and at other times it disappears and then displays a fake 126deg instead of the actual temp. I had a faulty thermistor in the past (2017 - 2 years after the pool went in) and it was immediately corrected with a new thermistor. This time around, I am not so lucky.

I did unplug the leads into the thermistor and put the 10K resistor directly into the top of the wiring harness leads into the thermistor pins on the board: same result... PS: I am using a 1/4W 10K resistor - doubt the watt value/resistor size matters but tought I would mention that.

Checked the High Limit and AGS sensors and both come up w a 0 ohms value so they both appear to be working.

I guess I will order the new board model w new membrane keypad. I found one on ebay for $400 with the seller offering free returns within 30 days. I could get another used board for $200 but I am so done w troubleshooting and not knowing 100% for certain the replacement board is good.

Thanks for the advice!
 
ajw22 said:
Where is the 126 from?
Click to expand...
The 126 is the highest reading the display will show for the temperature.

This means that the resistance is 3,312 ohms or lower.

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@mchartra, please don't start a new thread on the same topic.

That causes a loss of continuity and responders lose context.

Pentair MasterTemp 250 Error E01 - 126 -Not the Thermistor...

Hey gang. I am fearing that my control board has gone bad and before I take the plunge into an expensive replacement, I wanted to get some advice from smarter people than me on what else I could troubleshoot. -Would anyone by chance have a schematic for the board that shows logic flow? -I...
www.troublefreepool.com www.troublefreepool.com
 
JamesW - Thank you and apologies - good point in terms of keeping same issue within same thread. Duly noted!

Just measured the voltage with it running. 2.093 V (AC -True RMS) -which looks like 91deg according to the chart but I can tell you the pool water is definitely not that warm. :( My inline water temp per the Screenlogic app shows 79deg -makes sense to me.

PS - you mentioned DC Voltage but I think you meant AC. My meter is set to auto and it's measuring 60hz AC - if I force it to DC I get 0V.
Please take a look at the attached pics and LMK if this all makes sense.

Should I check voltage into the Board itself? If so, which pins should I hook the meter to? Looking at the wiring diagram, I assume black probe to the ground and red probe to which 24v Yellow wire or does it matter? My assumption is the 2nd connector to the right of the connector w the ground wire in the board. 2nd connector looks to feed directly off the transformer.

Thank you!
 

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The chart is from Hayward for the ProLogic, but I assume it works the same way.

Maybe it's different.

Zero volts DC matches the low ohms indicated by the reading so the board is probably reading a direct short.

Seems like a bad board to me.

What is the DC voltage with the thermistor disconnected and testing between wires?


 
Ah - yes -thanks -must be that Hayward's board works on DC while Pentair is AC - the Board is definitely 24VAC.

Thermistor disconnected reads per the chart. Not exactly sure of the current reading, but I've tried 3 different thermistors (in case one was bad) and they all check out unconnected. I even tested one in hot water and the resistance checked out w the chart.

The wires both show 0 ohms so they appear to be good as well. The only head scratcher is the 2nd board I borrowed from a fellow forum member exhibited the same behavior. It didn't fix my E01 error but then again, the member didn't really use the board so he could not vouch for it being fully functional.

I guess I'll need to just buy the new board and try that out. Could be an expensive test if it doesn't yield a fix...
 
mchartra said:
must be that Hayward's board works on DC while Pentair is AC
Click to expand...
I think that the thermistors all work the same way and probably take the same voltage.

The Hayward board has a component that converts the voltage from AC to 5 volts DC and I would think that the Pentair board would do the same thing because they use the same thermistors.

Maybe the problem is that the board is not outputting the correct voltage.
 

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