05 Chevy Cobalt cranks but won't start

I have a Cobalt that's giving me trouble. I ran code
diagnostics that lead me to the ECM. I replaced that. I've
checked battery, starter, spark plugs, ignition fuse, battery
fuse. It's cranking but not catching to turn over. Also, I now
have an imaginary code still showing as a check engine
light, but 2 separate code readers have been unable to
identify any current code that would lead to the engine light
being on. The dialogue box on the dash currently indicates
0 fuel, but ice got over half a tank. It's very cold here. Not
sure if that could be impacting this. Any suggestions?