Lennox G20 Series gas furnace - Igniter works, ignition flame is starts, but the main burners never ignite. Blower fan starts after appropriate period. What is wrong?

Lennox G20 Series gas furnace - Igniter works, ignition flame is starts, but the main burners never ignite. Blower fan starts after appropriate period of time. What is wrong?



Might be a dirty flame sensor. Pilot lights but no main burner right?

Look for a small metal rod positioned in the pilot flame, remove it and clean it with steel wool. Be careful it is fragile, remount and make sure the wire is attached properly


Hope this helps,