Hello all,
I have read through many post but can not find info on an error code 21. Any idea which direction I need to go with fixing this unit? Unit says 21 is a Gas Heating Lockout or Stuck gas valve relay. Does this mean I need to get a hammer and tap on that thing to unstick it? :D Any Help is greatly appreciated Thanks

Turn the power off to the unit wait at least one and a half hours for the control to auto reset. When repowering after the one and one half hours pay close attention to the start sequence. This will give us a much better idea of exactly what is happening. Pay close attention to the start sequence and do not cheat on the time out!

This is what I have.


21 GAS HEATING LOCKOUT - Control will NOT auto reset.
Check for: - Mis-wired gas valve -Defective control (valve relay)

Exact model numbers are also good to post.
This is not a hammer job. You will need a electric meter and know how to use it to test the components listed and the voltages to those components. There is a complete wiring diagram on the back of the blower door you can use for the testing purpose.

It is a model 58WAV111---14120. I am awaiting the 1 1/2 but assume it will be to no avail since it will not reset. I will have to get a volt meter I do not have anything to test actual voltage just the standard 110 220 440 etc testers.

I do want to thank you for the response. Next question of course is finding a gas relay? I can find the valves online but have not seen just the relay. Thanks again..

It will reset automatically after that time if the circuit board is doing its job.. You will have to test for voltage and possible OHM's. I cannot walk you through all the testing that is why I told you where the wiring diagram was. On most furnaces the valve relay is located on the circuit board and is not replaceable except to replace the circuit board.

Gotcha, I figured it was similar to a gas coil that was on top of the Gas Valve. Well time will tell, Thanks again

Alrighty, plugged it in turned it on the blower kicked on and nothing else. Now I have an error code 3 1... I did not see the glow stick light and obviously man did not discover fire tonight.

See what your unit says for code 31. It could be the silver pressure disc.

Yeah I am going to try that tonight, I see on here they say to "suck and blow lightly" and listen for a click. Thanks again

Alrighty, cleared the pressure switch plugged the unit back in... Blowers on glowstick glowed and then fire ignited.. unit ran fine. I ran it for a few minutes and shut it down. Let the blowers completely shut off and tried to restart it. Blowers on... glow stick glowed.. then went out no gas no fire and back to 31 code. I unplugged the unit for about 30 seconds then restarted it. Blowers on... glow stick glowed.. gas ignited and we have fire and heat. Unit ran fine for about an hour then flame went out blower stayed on and light blinking again.SOOOOO now what, replace the circuit board? This is the mother in laws house and she is cold should I quit trying to save a buck and call a repairman? Seems to me unit is working fine just has the gas relay bug. As always advice is appreciated and respected. Thanks

Alrighty, cleared the pressure switch plugged the unit back in... Blowers on glowstick glowed and then fire ignited.. unit ran fine. I ran it for a few minutes and shut it down. Let the blowers completely shut off and tried to restart it. Blowers on...glow stick glowed.. then went out no gas no fire and back to 31 code. I unplugged the unit for about 30 seconds then restarted it. Blowers on...glow stick glowed.. gas ignited and we have fire and heat. Unit ran fine for about an hour then flame went out blower stayed on and light blinking again.SOOOOO now what, replace the circuit board? This is the mother in laws house and she is cold should I quit trying to save a buck and call a repairman? Seems to me unit is working fine just has the gas relay bug. As always advice is appreciated and respected. Thanks


I wish you would have told me it was your mother in laws house to start with. No matter if you do fix it she would still say it is not working like before. LOL

Jump the pressure switch electrical connections and see if it will cycle a few times without kicking a code. Also check the pressure switch rubber hose carefully for a small hole tear etc. If the unit runs OK with the switch jumper you have found the problem if not call for On site service before it becomes a memerable occasion and comes up every Thanksgiving. LOL

NOTE: Do not allow the furnace to operate with the connections jumpered unattended. This is for test purposes only and could create a dangerous condition if allowed to operate without you being there. (now that is a thought if you do not like your mother in law and are looking for a quick disposal).

I hate to see you buy a board if it is not necessary.

Note if this system has a flame sensor clean it up a bit with sand paper to possible prevent another problem down the road. Clean it carefully and stay away from the ignitor. They are very sensitive.