I have a luxaire 92% efficient multi stage variable speed furnace. It's at a cottage and it one year old. The furnace shuts off (locks out) and will not restart until I turn the system off/on and then it will immediately start up and work again. I may run for a week or two or even a month. What is the issue? I have replced the mother board but it still does the same thing.

Check to make certain that the vent has a good slope back to the furnace at all locations. Then make sure that it has good drainage. Those are the two biggest culprits for that problem.