Short answer: short-cycling, where a furnace runs for a few minutes, shuts off, and starts again, is usually airflow, flame sensing, overheating, or settings, not a single mystery fault. A clogged filter or blocked return overheats the heat exchanger and trips the limit switch. A sooty flame sensor shuts the furnace down minutes after startup. Wrong thermostat cycle settings, or a furnace oversized for the home, can short-cycle by design. Every startup wears the ignitor, inducer, and motors, and a furnace that never completes a cycle heats unevenly and wastes gas, so the fix is finding the cause, not resetting the furnace and hoping.
Check the filter and vents first. After that, the cause needs testing: flame signal, limit switch behaviour, temperature rise, and thermostat settings, in that order.
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