Hi all,

I am trying to troubleshoot the issue the furnace I've been having for a week. Initially, control board was dead. I called a technician and he said that I need a new control board and pressure switch. I got pressure switch and I've gotten a used control board. Turned out the pressure switch wasn't an issue, more of a control board problem which actually resolved my issue partially. Now at least furnace or fans will turn on, but will shut off and restart within a few seconds. I thought it was a dirty flame sensor. I cleaned it up with a sand paper.


I am getting 5 blinks which read differently in manual and back panel:

Manual: Flame sensed with gas valve off.

Back Panel: Flame sensed when no flame should be present


Watch video with sound:
YouTube - Can tell what's the issue with this furnace?

Any suggestions what could be the cause of this issue? Bad control board? Bad flame sensor? Anything else? I am pulling hair on this, so any help will be appreciated!

A flame sensor will not go bad, just gets dirty. I would say you are still having control board problems. or I had one do that 1 time and it ended up being the gas valve. But I ould take the odd of it still being the control board if you say it was a used 1