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M Oglesby
M Oglesby, HVAC Technician
Category: HVAC
Satisfied Customers: 2038
Experience:  Universally Certified HVACR Technician
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How do I fix ignition lockout of my furnace due to retries?

Customer Question

My furnace keeps faulting out. It says ignition lockout due to retries. What does this mean and what would I do to fix it?



Submitted: 6 years ago.
Category: HVAC
Expert:  M Oglesby replied 6 years ago.

M Oglesby :

Hello, Welcome to JustAnswer.

Customer :

Hello, would this be the result of a dirty flame sensor

M Oglesby :

Yes. The flame sensor needs to be cleaned with a piece of emery cloth or sandpaper.

Customer :

Is that about the only thing I should try.

M Oglesby :

That is the only thing that it could be unless your control board is bad.

Customer :

Ok thanks and I will try that. Everything else on the furnace seems to be in proper working order. This problem just occurred over night.

M Oglesby :

But I am pretty sure that is the problem.

Customer :

Ok, thank you.

One more question. The flame sensor should be two wires attached and on the side of the burner right?

M Oglesby :

The flame sensor should have only one wire and is located in the path of the burner jets.

The igniter has two wires.

Customer :

Ok my burner has two elements on each side and they both have two wires going to them both. That is all I see on that box.

M Oglesby :

Describe to me how the elements look?

Customer :

It is a Coleman furnace, if that makes a difference.

M Oglesby :

The flame sensor rod is a small thin steel rod that is straight or L shaped.

Customer :

They have two prongs on them with electric connectors hooked to them.

Ok, I will have to pull this and see if it is the rod you are speaking of.

You were right. I guess my next question would be, would you be able to tell me were the flame sensor is?

M Oglesby :

It is usually located near the pilot igniter or in the path of one of the burner jets.

Locate it and let me know if you find it.

Customer :

I have a small box about 10wX6dX4t. It has a sight glass were you can see the pilot come on but the only wires attached to it are on the left and right side of the box. Both of these have two wires going to them. Same color wires at that and these when unscrewed from the box they are just flat little round plugs.

M Oglesby :

Ok give me a few minutes.

Customer :

Ok, I found that flame sensor. Took it out and used some emery paper, cleaned it and put it back. Reset the fault and fired it up and I'm still getting the same fault ignition lockout

The flame sensor is in good shape. It had very little amount of debris on it

M Oglesby :

You have to scrub it very very good.

That was quick.

Customer :

So even if it looks clean it still might need some more scrubbing?

M Oglesby :

That is correct. Especially on the tip of it.

Customer :

Yes, it was kind of hidden but it was right on top of that box all the way to the back

Should I be worried about cleaning it too much or give it a good scrubbing?

M Oglesby :

Give it a good scrubbing.

Customer :

See, I didn't concentrate so much on the tip. I will try it again.

M Oglesby :

If cleaning it does not correct your problem, you will have to call a technician.

Customer :

Yes, that didn't do the trick and it is clean. Looks brand new. Otherwise you think it was what?

I have a technician on the way

You think it could be that board

M Oglesby :

I apologize that we could not solve your issue.

Do the burners ignite at all?

Customer :

Yes, the burner ignites but it kicks back off. It does that three times and then faults out

M Oglesby :

It could be a number of things.

It could be a loose or broken ground wire some where

Or it could be that the control board is gone bad.

Customer :

Ok. Those control boards are probably pretty expensive.

M Oglesby :

The control board itself will cost about $175.

The labour will be another $200.

Customer :

The other thing I noticed is, usually when I had this problem I would throw my thermostat on and off and it would work great

M Oglesby :

Well whatever it is hopefully the technician will find it.

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