The furnace lights, then quits on you
You hear the familiar click, the whoosh of ignition, maybe thirty seconds to a minute of warm air, and then everything shuts off. Not a slow fade, a hard stop. A few minutes later you can usually get it to light again, and it does the same thing. If this is happening on a cold night in the Ozarks with the temperature dropping into the 20s, it feels urgent, and it is worth taking seriously, but it is also a very specific kind of problem with a short list of usual causes.
Why this shows up so often around Nixa
A lot of the housing stock in and around Nixa, Ozark, and Christian County was built from the 1990s through the 2000s, with furnaces that are now old enough to be showing their age but not so old that people have replaced them. These are mid-efficiency or high-efficiency gas units, often in a crawlspace or a closet, and they tend to develop this short-cycle symptom right around the first hard cold snap of the year, which in this part of Missouri usually means late November through January.
The reason timing matters is that a furnace that has sat idle since March gets a workout the first time it has to run for hours instead of minutes. Dust that built up over spring and summer gets pulled through the system, pilot assemblies and flame sensors that were marginal get pushed past the point where they can keep working, and anything that was a minor issue becomes a furnace that won't stay lit.
More on this from A Furnace That Lights Then Shuts Down Seconds Later.
What's actually happening when it shuts down
Almost every furnace built in the last few decades has a flame sensor, a small metal rod near the burners that confirms a flame is actually present. If the furnace can't verify that, it assumes something is wrong and shuts off the gas as a safety measure. That's the shutdown you're seeing. The usual cause is a flame sensor coated with a thin layer of carbon or oxidation, thin enough that you often can't see it, but enough to break the signal.
Other common causes include a dirty flame sensor wire or loose connection, a cracked or weak sensor, draft problems in the vent pipe, or a dirty air filter restricting airflow enough to trip a limit switch. Less often, it's an issue with the igniter cycling in and out, or a control board losing communication with the flame sensor circuit.
What you can check before calling anyone
Start with the filter. If it hasn't been changed since last winter, swap it now. A clogged filter restricts airflow, overheats the heat exchanger, and trips a safety switch that looks exactly like this problem from the outside. It's a five minute job and it rules out the easiest cause.
After that, check that nothing is blocking the vent pipe outside your house. Leaves, a bird's nest, or a chunk of ice from a recent freeze-thaw cycle, which happens often here given how Ozark winters swing between mild and single digits, can restrict exhaust enough to cause a shutdown. If the outside vent cap looks clear and the filter is new and the furnace still won't stay lit, you've likely narrowed it down to something inside the furnace itself.
Where this stops being a DIY job
Cleaning a flame sensor with fine sandpaper or steel wool is something a comfortable homeowner can do, but it means shutting off power and gas to the unit, removing the correct panel, and finding a small rod near the burner assembly without disturbing anything else. If you're not sure you can identify the flame sensor from the igniter, this is where it's worth having someone who does furnace repair in Nixa take a look rather than guessing.
Any job involving the gas valve, the control board, or the heat exchanger should go to a technician. A cracked heat exchanger can leak combustion gases into your home's air, and it's not something you can diagnose by eye in most furnace designs. If your furnace is repeatedly shutting down and you've already checked the filter and the vent, that's the point to stop troubleshooting yourself and get it looked at properly, especially with a Missouri winter settling in and the furnace needing to run reliably for the next few months.