It is now about 57 degrees in my house. My furnace just turned on but there was no ignition, no flame. I could hear the blowers running. Is my flame sensor bad or dirty? Or is it something else? How do I fix this? I have fixed my furnace before with a new flame sensor or something like that. I would have to research it. But it only cost me around $52for the part about 6 years ago.

Thanks.

It could be the flame sensor. Try cleaning it before replacing. You can do a search here and find many flame sensor problems.