This furnace has had several different problems. The main problem was the circuit board. The replacement is 65K07, which so far has been reliable. They also had an update on the ignitor and sensor assembly. They changed it because when it would go to light the spark would go to ground sometimes at the blue spark wire down under the burner. They also had a problem with the inducer motor and was updated. It would cause the pressure switch to open as it was not strong enough. When I check out a G24, the first thing I do is watch the pressure switch with an ohm meter and see if it is opening up. The way the flues are run is very critical as they have to be run exactly as shown in the instruction manual. I saw brand new G24's that would go out on pressure switch as they were vented improperly. If has an older style board, this could be the problem, but other things need checked to confirm this.