Lennox 80UHG does not ignite?

The l.e.d lights indicate "Primary and secondary limit switch open" This happened last year and I opened and closed the door a couple of times and it worked fine all year. I turned on the heat and the same thing happened...same error message. Once again after a few minutes it fired up. I dont think it is the board or it would not have fired up at all??? As soon as I turn it on the fan starts right away and does not have time to ignite....HELP PLEASE