Situation: Nest thermostat shows that the furnace is running, but its not and no error codes are displayed on the furnace. This happens about once per day where it seems the furnace doesn't ignite properly. I finally saw the behavior first hand... The furnace actually lit on the first or second try but then went out after about 3 seconds.
If i turn down the heat, the Nest app shows that the heater isn't running, then I wait 10 seconds and turn the heat back up and the heater ignites successfully. Any ideas why it would light, then turn off and not throw an error code?