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Furnace Keeps Shutting Off (Short Cycling)

A furnace that starts then shuts off within minutes often has a dirty flame sensor, clogged filter, or overheating limit switch. Check the filter first; sensor and limit repairs typically run $100–$600.

Reviewed July 2026

What does furnace keeps shutting off (short cycling) mean?

Short cycling means the furnace heats briefly, shuts down, then tries again — repeating every few minutes. This wastes energy and stresses components. Restricted airflow and flame-sensor faults are the most common causes on modern units.

What usually causes furnace keeps shutting off (short cycling)?

Dirty flame sensormost common

Typical repair: $100–$300

Clogged air filtercommon

Typical repair: $20–$75

Tripping high-limit switchcommon

Typical repair: $150–$600

Find your exact error code

Select your furnace brand to jump to the code page for this symptom.

Carrier13Limit or rollout circuit lockoutBryant13Limit or rollout circuit lockoutTempstar4 FlashLimit or rollout circuit openLuxaire3 BlinksPressure-switch circuit did not closeRheem13Flame was lost during operation

What should I check first when furnace keeps shutting off (short cycling)?

  1. Replace the air filter — this fixes many short-cycling cases.
  2. Open all supply and return vents.
  3. Note whether burners light before shutdown; no flame points to a sensor issue.
  4. Call a pro if the cycle repeats after a filter change.

What a repair costs

A flame sensor cleaning or replacement typically costs between $100 and $300 nationally.

Typical repair cost
$100 – $300flame sensor cleaning or replacement
Where the money goes
Part $15–$75Labor $25–$285Typical labor time: 0.5 hrs

This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.