I'm having service problems with my G20 furnace. The ignitor has been replaced several times in the last five years. the furnace seems to give up after a long period (4-5 minutes) of sparking and blows cool air. When this happens the main burner fails to come on.
The dealer says it is because the furnace is in the laundry room (?)
I can get at the ignitor like the service tech and clean the ignitor probe with a toothbrush and it works for a while ( up to 8 hours).