Hi my york Fg8d10020mu11a will not light. Replaced flame sensor still no gas. Ignitor glows bright 3 time, no gas and no fire flash code of 7 to many retries.

Before this, I was able to cycle power and the system ignited and ran for 4 min and stopped. Did this a couple of times then it worked for half a day and not it will not light at all.

Any Ideas?

Update. Re-seated the big square connector and all is well. So first turn off power and reseat big square connector on control board.