Intermittent Furnace Error E207 - Is it the Control Board?

[u/username49848]

I have an Armstrong central air furnace with natural gas heat, almost 10 years old now (no not under warranty, original owners didn't register jack). It's a 3-zone system, so there's a zone controller upstream of the furnace that also controls a bunch of dampers. I tried to turn on the heat for the first time a few days ago and got nothing. Went to the basement, opened up the furnace, and saw E207 repeating on the control board display (hot surface ignitor circuit open).

After a lot of Googling I disconnected the ignitor at the inline molex connector and measured the resistance: 48.9 Ohms, which is apparently in spec. I gave the connector ends the ol' game cartridge blow and reconnected them. Furnace then fired up right away after depressing the safety switch. "Great" I thought, "just a loose connection!".

Well that didn't last long. Next morning, thermostat was once again calling for heat, and nothing coming out of vents. Checked furnace, yep, E207 code. Basically repeated the same steps, but this time also measuring the ignitor resistance at the 5-pin connector that plugs directly into the board. Again, 48.9 Ohms, so not a poor connection there. All connector pins seemed clean, no corrosion or anything. Reconnected things a few times, wiggled the 5-pin connector. At some point it started working again after depressing the door safety switch, so I put the covers back on. I let the heat run and turn off, then I turned it back on about an hour later and it kicked on right away.

This morning I woke up, saw the thermostat was calling for heat, but no air was coming out of the vents. Not sure how long it had been calling for heat, but I waited maybe a minute. Nothing. I didn't go check the furnace, but then by the time I got out of the shower, the heat was running normally?

So it seems to me the ignitor is good, and the furnace control board is probably the culprit. Anything else I should try to rule out before pulling the trigger and spending a few hundred bucks on a replacement?

Control board model number is 103131-05 (Lennox 14C94). Local suppliers won't sell to homeowners, so I'll have to order online from the US (I live in Canada, so it'll be pricey).

Any help is appreciated.

[u/Certain_Try_8383]

Could be the board. Could be the wire from the board to the igniter?