No thermocouple on it. Electric igniter. Strange problem. Now it seems to work fine. I'm going to fall off my wallet and get it checked out by a pro.

Unit runs about 30 secs and flame goes out. Runs a couple of minute and tries again with same result. After a few tries furnace shuts down with failed ignition code. I replaced the igniter/ flame sensor but issue remains. Any thoughts on my next avenue to try? Need to fix soon as it is -25c here.