Flame lights but goes out
I have a Ducane furnace model MPGA100B4B, the furnace will light but the flame goes out after a few seconds. I have changed the igniter and it still does the same. The flame seems to go out even when the igniter is still glowing. I can hear the gas valve shut off. It started only doing this once in a while over the past few months and after a few tries it would go. Could it be the transformer for the gas valve or is there a switch involved?

Thanks
Brent

Clean the flame sensor.