My 04 Hyundai accentg will not starftg when it gets bel;ow 10 degrees F. Above 10 it starts fine. Below 10 it just cranks with no start. No hiccups, no kind of caught. Just cranking on and on. There are no codes in the computer. Replaced spark plugs and reduced the gap. Replaced the coil pack, etc. Garage wants t try the crankshaft position sensor next. It started this 3 years ago. Before that it started fine in all weather.
How old is the battery?
I would try replacing crank sensor.
I’ve seen these sensors fail in both hot/cold weather.
I think Tester is on the right track to expect an ignition system problem. But first try the key dance: turn the key to Run, not all the way to Start, then back to Off after a few seconds. The fuel pump should run for a few seconds each time you turn it to Run. Do this a couple or few times. If it starts, your problem may be with the anti-drainback valve in the fuel pump, or maybe a leaky injector. And if it starts and you any everyone who uses the car knows the key dance, you can decide whether or not to do any repairs.