[jsb5717]

Ah, so it’s actually igniting before it fails? That’s different. There are a few things that could be.

Propane valve - it’s possible it’s not putting through enough propane
Propane regulator - same issue. I’ve seen both of these fail on different furnaces
Limit Switch - Easiest and cheapest to try. You can just jump/bypass this switch and see if the furnace works.

Without the proper testing equipment it’s difficult to know for sure which component is failing. I have a replacement component for most everything on my furnace so I don’t get stuck without heat and it’s easier to troubleshoot.