It seems odd that it shut off during the fire, but I think you will find that most report that the "auto" function is a bit flaky at best. I think it is related to the fact that they sense the temperature under the stove rather than on top of the stove. In my case I find that it pretty much stops working in auto when I have a fare amount of ash in the stove. I think that the ash insulates the bottom and lowers the temperature where the snapstat senses. I don't really use auto at all anymore. When I do use it I flip it to auto when I go to bed so that fan doesn't run all night. But sometimes that just shuts it off even when a roaring fire is going. I'd say empty the ashes and try it again.