E05 error on Pentair master temp 400HD

[farreljs]

Hello, yesterday I started getting an E05 error on my Pentair master temp 400 HD. I opened the heater up and put a multimeter across the flue temperature sensor and I got 3.8 ohms. So I’m assuming that the temperature sensor is OK.
The air intake is also fine and from what I can tell the water flow into and out of the heater is unchanged.

The heater will run for about 30 seconds to a minute and then shut off, which time the error message shows in the service here light comes on.

Should I just replace the temperature sensor anyway, as this seems to be the most common cause of this problem? I am just hesitant to do so since the multi meter is not reading zero ohms.

I did press the pool button and hold it while the heater was running and it just said 40. Yesterday when I pressed it there was actually a temperature reading of about 250°.

It’s a full week until someone can come out and look at my heater, which means I may not have a heater for the Fourth of July weekend. I would appreciate any help help you can provide. Thanks!

 

[Poolbreh]

You should still check flow make sure no external bypass is open. I would pull the bottom bolt on the manifold and see if there is water in the combustion chamber. Are you sure the 40 wasn’t between cycles? I would try again and see how high it gets. What is the current water temp? If you have an infrared laser gun, you can check the flue temp and compare.

 

[JamesW]

New SFS but heater will not work.

The alternating 40/80 usually means the the circuit board is not getting a good reading from the stack flue temperature sensor. Check the stack flue temperature sensor with a good ohmmeter while the sensor is cool. It should read 3.8 megaohms. Check the wires from the circuit board to the...

www.troublefreepool.com

 

[farreljs]

The water temp is about 73. I will check the manifold for water and also re-check the stack flue temp and reply back. Thank you!

 

[Poolbreh]

Did you check the links JamesW posted?
He’s come across this a few times. If the ohms check out and wiring is good and stack flue temp continue to register at 40. It’s a problem with the board measuring resistance.

 

[farreljs]

Yes. I see that post now. Thanks! I will check the wires from the sensor to the board tonight. I appreciate the help and will follow up shortly.

 

[farreljs]

Hello. All the wiring looks intact to the board. I am not savvy enough to measure continuity though. There is water in the manifold. The resistance across the SFS is 4.0 ohm.

The only thing that has changed is that there is now a symbol on the left side of the display which I presume represents the SFS. So I am assuming that the control board is telling me to replace it?

 

[JamesW]

The picture is not clear enough to see the symbol.

I would try a new sensor.

 

[ps0303]

Look at the back of the board. It has LEDs on it that light up helping to show you what the error is for. Have you done this?