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FIXED LDG3016ST LG F9 Code on Upper Oven

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csquared63

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Model Number
LDG3016ST
Brand
LG
Age
1-5 years
Hi,

My LG upper oven is throwing an F9 error. From what I have read, it could be related to the temperature sensor, but we have never used the cleaning option, nor has it ever overheated.

I assumed it was the igniter, because it did not glow at all before displaying the code, but after replacing the new one doesn't glow either.

Any thoughts on where to look next?

Thanks,

Carl
 

Dan O.

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Not heating

My LG upper oven is throwing an F9 error.
This is for a different LG range model but is pretty likely the same on yours:

F-9 - No heating (Upper) - If oven temperature in the UPPER oven does not exceed 150°F (66°C) in less than 5 minutes.

after replacing [the ignitor] the new one doesn't glow either.
Did the old ignitor test as defective?

I don't have a wiring diagram for that model to see what all the possible causes could be. Other than the ignitor, the upper oven side of the gas valve is definitely a possibility as is part of the electronic control system.

LINK > LG LDG3016ST Oven Gas Valve

The control system looks to incorporate several different electronic control boards. I do not know which particular one might be most suspect for causing your symptom.

I also don't know if there any any thermal protectors in the electrical circuit to the ignitor that could stop its heating. There might also be the possibility of a burnt, broken or loose wire in the ignitor circuit.


Someone might need to trace the wring circuit to the ignitor on the appliance's wiring diagram to see what might prevent power from getting to the ignitor.

JMO

Dan O.
 

csquared63

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Thanks for the reply and ideas, Dan. I did not test the old igniter, though I saved it just in case it wasn't the issue. I had a similar problem with the furnace years ago and replacing the igniter worked. I guess I was lucky!

Regarding the wiring diagram, I scanned a few pages from the tech papers and attached as a PDF. The F9 error does mention the gas valve, but there are a few other things beyond my pay grade. I have a friend with a multimeter that I'll have to consult, but if you are so kind to take a look at the attachment and let me know if you have any other ideas I would appreciate it.

Thanks again for your previous input!

-Carl
 

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  • LDG3016ST_Wiring-Troubleshooting.pdf
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Dan O.

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My LG upper oven is throwing an F9 error.
It looks like the upper oven has separate bake and broil burners. Did you try the upper oven on both bake and broil?


Dan O.
 

Dan O.

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the wiring diagram, I scanned a few pages
From the wiring diagram, it looks like the oven ignitors and gas valves are fed directly from the control system's relay board. There does not appear to be any safety devices in the circuit that could be responsible.

In that case for a new ignitor to not glow at all, either the gas valve could be electrically open or the control is not powering them. The latter could be due to a problem in the control relay board (see the following link) or a problem in the wiring to that ignitor and valve.

LINK > LG LDG3016ST Power Control Board aka Relay Board

For the gas valve to prevent the ignitor from glowing, it would have to be electrically open so a simple continuity test of the upper oven's portion of the gas valve should reveal if it was responsible.

LINK > LG LDG3016ST Oven Gas Valve


You can read about hot an oven's hot surface ignition system works at the following link. (see the section on Electronic Ignition with Glow Ignitor.) It also mentions a 'dual' gas valve like used on your model (although it looks like yours has a dual valve plus a single gas valve making 3 in total.

LINK > Understanding Gas Oven Ignition Systems


Dan O.
 

csquared63

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I finally got around to testing the gas valve. Strange, but I only see the one dual valve on the lower left side, but it definitely was the one with the gas lines to the upper oven. As I said previously, the broiler works, so if this valve is controlling the single ignitor which is responsible for both the upper broiler AND oven, then it's probably not the valve. As you can see in the attached photo I had continuity. The other two sets of connections on this valve showed the same results.

I guess it's time to call "the appliance guy." I'm not sure how to test the relay board.

Thanks again for your input.

-Carl
 

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Dan O.

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2 Gas Valves, 1 a dual valve

I only see the one dual valve
It only has 1 dual valve but it also has a separate, single gas valve. I don't know which is for which oven burner.

20180228_145908 - Copy.jpg

if this valve is controlling the single ignitor which is responsible for both the upper broiler AND oven
Each burner will have a separate ignitor and separate associated gas valve. A 'dual' gas valve will control gas to 2 burners, possibly bake and broil in the same oven cavity. Each side of a dual gas valve functions independently from the other as described at the 'Understanding Gas Oven Ignition Systems' link I supplied previously. It's possible for 1/2 to fail but the other left unaffected.

JFYI

Dan O.
 

csquared63

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It only has 1 dual valve but it also has a separate, single gas valve. I don't know which is for which oven burner.

Each burner will have a separate ignitor and separate associated gas valve. A 'dual' gas valve will control gas to 2 burners, possibly bake and broil in the same oven cavity. Each side of a dual gas valve functions independently from the other as described at the 'Understanding Gas Oven Ignition Systems' link I supplied previously. It's possible for 1/2 to fail but the other left unaffected.

Thanks Dan. I tried all three connections in that photo. They all read the same. I assume that would eliminate the valve as the culprit?
 

Dan O.

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Valves all test the same

They all read the same. I assume that would eliminate the valve as the culprit?
If none of the valves test electrically open (aka infinite resistance), they are not the cause of the one ignitor not glowing. That only leaves the control PCB itself or a very slim chance, a wiring problem to the malfunctioning ignitor.

LINK > LG LDG3016ST Power Control PCB

JMO

Dan O.
 

csquared63

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If none of the valves test electrically open (aka infinite resistance), they are not the cause of the one ignitor not glowing. That only leaves the control PCB itself or a very slim chance, a wiring problem to the malfunctioning ignitor.

OK, well then since the ignitor does work for the broil function, I would suspect the PCB over the wiring. Thanks again for your input!

-Carl
 

Dan O.

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csquared63 said:
No luck with the PCB.
  • Check the wiring circuit from the control to that ignitor.
  • Recheck your previous continuity test of the gas valve for the broiler.
  • I would assume the new ignitor you installed is good but test it too to be certain it isn't the problem.
Those are the only things shown in the wiring circuit to that ignitor that could totally prevent it from glowing besides the control system.


Which PCB did you replace? There are several in that range. What was the part number you replaced? Did you purchase a new part or a used one??


icon3.png
When you were testing the gas valves, did you remove at least one of the attached wires? Failure to do so could give false readings.

LINK > How do I test for continuity?


JMO

Dan O.
 
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csquared63

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  • Check the wiring circuit from the control to that ignitor.
  • Recheck your previous continuity test of the gas valve for the broiler.
  • I would assume the new ignitor you installed is good but test it too to be certain it isn't the problem.
Those are the only things shown in the wiring circuit to that ignitor that could totally prevent it from glowing besides the control system.

Both the oven and broiler igniter read 133 ohms. Could be a voltage issue, though I'm not super comfortable testing with the power on.

Which PCB did you replace? There are several in that range. What was the part number you replaced? Did you purchase a new part or a used one??

Oven Relay PCB - EBR71261601 - "New"

When you were testing the gas valves, did you remove at least one of the attached wires? Failure to do so could give false readings.

I did, yes. I removed both wires on all three connections. All connections read 2 ohms.

I also tested the temperature sensor and got 1083 ohms.

Maybe the PCB board I received was bad? How can I be sure?

Thanks again for the reply!

-Carl
 

Dan O.

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Could be a voltage issue, though I'm not super comfortable testing with the power on.
If it's not glowing at all, it's not getting power... period. We need to determine where that stoppage is.


Both the oven and broiler igniter read 133 ohms.
As long as it doesn't have infinite resistance (ie. NO continuity), it is not the cause of the ignitor staying cold.


Oven Relay PCB - EBR71261601 - "New"
Good. Just trying to rule out possibilities.
icon14.png



Maybe the PCB board I received was bad?

A defective "new" part is very unlikely. I would suggest every other possibility be eliminated before even thinking that might be the cause. It is a very rare occurrence.

How can I be sure?
If someone can isolate the connection on the PCB to the upper oven bake ignition circuit, testing there for voltage when that burner should be ON would tell if the control is responsible for no power getting to that function. If power WAS there but not getting to that malfunctioning burner, that would leave the ignitor (unlikely with your reported testing results), the oven gas valve (unlikely with your reported testing results) or their wiring. However, that would require testing on a 'live' appliance which can be dangerous. I don't know any other way to eliminate the control as the cause.

I'm sorry but i don't know what else to suggest.

Dan O.
 

csquared63

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OK, thanks. No need to apologize! You have been very helpful in explaining how to troubleshoot. I will need to check with a friend or two to see if they have experience testing voltage on a live appliance.

I'll report back when I have a chance to test. My wife is getting antsy with Easter coming!

Thanks again for your help!

-Carl
 

csquared63

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Solved!

So I tested the voltage out to the igniter and it was normal. I figured I should re-check the igniter continuity. Now that I think of it, I think I only measured the resistance, or maybe as a novice repair guy I was doing shoddy testing!. No continuity in the igniter! I saved the old igniter that I originally swapped for the new in the broiler position, and put it in place of the bad lower igniter and voila!

Well, at least I learned a lot. :3:

Thanks again for your input, Dan. The world needs more people like you! :applause:

-Carl
 

Dan O.

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.
You previously said, "I assumed it was the igniter, because it did not glow at all before displaying the code, but after replacing the new one doesn't glow either."

So that referred to replacing the broil ignitor and not the bake ignitor??

Dan O.
 

csquared63

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Yes, I was looking at the broil igniter when I attempted the bake, after I had already replaced with the new. I just didn't educate myself enough about the system.

So now the new one is in the broil position, and the old which was in the broil is now in the bake!
 
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