My furnace will run fine for a while then go into lockout (2 flashes). It goes into lockout when it tries to start up normally. It does everything normally except when I here the gas valve click it just doesn't light. No flame at all. Inducer, elec. Igniter work fine. I'm getting voltage to gas valve and here it click but no flame. There is an air tube that also goes into the gas valve, not sure if it would be an issue. After I reset the furnace by shutting off elec. To it, it will usually light. Any ideas? Thanks

Good job of describing the symptoms you are experiencing, and your investigation of those symptoms has been good!

You have gas to the furnace since it will light up sometimes. The gas valve doesn't open reliably even when you apply voltage to it directly. That means you have a failed gas valve which needs to be replaced.

I recommend against DIY gas valve replacement because the gas valve needs to be adjusted to work with the individual furnace.

Good luck!