Pilot Light Keeps Going Out? What It's Telling You

If your furnace is old enough to have a standing pilot, it's old enough to have earned some quirks. A pilot that keeps dying is almost always one of three things — and the flame itself tells you which.

Safety first, every page, and doubly here: if you smell gas, do NOT relight anything. Leave the house and call your gas company from outside. Wait several minutes after any pilot goes out before relighting, so raw gas can clear.

1. The thermocouple is dying (the usual one)

The thermocouple is a small metal probe sitting in the pilot flame. Its whole job: prove the flame exists, so the gas valve stays open. As it ages, it proves it more weakly — until the valve stops believing and shuts the gas. Pilot lights fine, runs a while, dies. Repeat.

The telltale: the pilot lights normally and stays lit while you hold the button, then dies seconds or minutes after you release it. Thermocouple replacement is one of the cheapest, most routine repairs in HVAC.

2. The flame is weak or the wrong shape

A healthy pilot is a steady blue cone that wraps the thermocouple's tip. A lazy, yellow, flickering, or split flame — often from a dirty pilot orifice — may not heat the thermocouple enough to hold the valve open. Yellow and lazy = dirty. That cleaning is a pro's ten-minute job.

3. A draft is blowing it out

Pilot dies only on windy nights? Only when the laundry room door is open? A draft from a vent, a chimney downdraft, or even a furnace-room air leak can snuff a pilot. The pattern — when it dies — is the clue worth writing down before you call.

Safe to try yourself

Relighting per the instructions on the furnace's label is a normal homeowner task (hold the button the full 30–60 seconds the label says — releasing early is the #1 relight failure). Replacing a thermocouple is borderline DIY. Anything involving the gas valve itself: pro, no debate. A gas valve that won't hold with a NEW thermocouple is a failing valve — stop relighting and call.

Related symptoms

• Furnace won't turn on
• Furnace clicks but won't ignite
• Smell gas from the furnace

Start the free troubleshooter → Free, no sign-up. It asks when it dies — because the pattern is the diagnosis.

Free · no sign-up · no personal info · about ten minutes