Tempstar furnace, pilot light turns on then off in 1 second
Check to make sure the wiring for the flame sensor is properly connected, and the wire is not damaged. If that all seems good. Replace the flame sensor.  If the pilot is not proving, it's almost certainly because the flame sensor is not detecting it.  

Flame sensors do go bad, but are typically a cheap replacement. However, it looks like the sensor in your furnace is part of a pilot assembly So it will be a bit more expensive, and a bit more difficult to replace.