This is a Carrier Comfort 80 58DLX155.
Turned out the cause was a faulty earthquake valve ( [ Ссылка ] ). I live in California and the earthquake valve on my side of the meter had partially tripped, restricting but not stopping the flow of gas. I had PG&E come out and take a look. After they tested pressure at the meter (which turned out fine) they reset the earthquake valve and everything works again.
Here's what an earthquake valve looks like : [ Ссылка ]
![](https://i.ytimg.com/vi/POQBXLhgCao/maxresdefault.jpg)