Batbc

I have a 2006 Fleetwood Pace Arrow with an Atwood furnace model 8531-IV. Until today it worked fine. Now it ignites but quits after a few seconds and cycles through 3 times. I notice then a red flashing LED on the motherboard after the cycle with 3 flashes then a pause before 3 more. The manual says the code indicates "ignition lockout fault". What can I do?