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Fix a gas fireplace that will not stay lit

We'll confirm the symptom, check the pilot flame and thermocouple, clean the orifice, and rule out draft—or tell you when to call a pro.

Troubleshooting · Home appliances
10–30 min
What you'll need
  • Fine-grit sandpaper or soft cloth (for cleaning thermocouple)
  • Needle or compressed air (for orifice cleaning, optional)
  • Replacement thermocouple (if tests show a fault; match part number)
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Steps

Goal: Confirm the symptom, rule out gas smell, then isolate the cause—thermocouple, pilot orifice, or draft.

  • Turn the control knob to pilot, press and hold to light the pilot. Keep holding for 30–60 seconds. Release.
  • Good: Pilot appears but goes out when you release—symptom confirmed. Proceed to Check for gas smell.
  • Bad: Pilot does not light at all—different problem. See When to get help.

Gas smell check

Goal: Confirm there is no gas leak before troubleshooting.

  • Step back and sniff. Gas has a rotten egg odor.
  • Good: No gas smell. Proceed to Thermocouple path.
  • Bad: You smell gas. Evacuate immediately. Do not turn anything on or off. Call 911 or your gas utility from outside.

Thermocouple path

Goal: Check and fix the thermocouple and pilot flame.

  • Check the gas supply valve. Handle parallel to the pipe = on. If closed, open it and wait a minute.
  • The thermocouple is a thin metal rod next to the pilot flame. It must sit in the flame tip. If bent away or dirty, it will not heat and the gas valve will close. Gently bend it toward the flame. Clean the tip with fine-grit sandpaper or a soft cloth.
  • Confirm the pilot flame is strong and blue, not yellow or weak. You should see the thermocouple tip in the flame.
  • If the pilot is weak, turn off the gas and clear the pilot orifice with a needle or compressed air—do not enlarge it. Turn the gas back on and light the pilot.
  • Light the pilot. Hold the knob for a full 60 seconds. Release slowly. If it stays lit, the fix worked.
  • If it still goes out, shut off the gas at the supply valve. Disconnect the thermocouple and replace with an exact match (match the part number). Restore gas and light the pilot.
  • Good: Pilot stays lit when you release the knob.
  • Bad: Still goes out after cleaning and replacement—check for draft or call a technician.

Clean orifice

Goal: Clear a clogged pilot orifice so the pilot flame is strong.

  • Turn off the gas at the supply valve. Locate the pilot orifice (small opening where gas feeds the pilot).
  • Use a needle or compressed air to clear debris—do not enlarge the opening. Turn the gas back on and light the pilot.
  • Good: Pilot is strong and blue. Proceed to Thermocouple path if it still goes out.
  • Bad: Orifice damaged—replace the pilot assembly or call a technician.

Draft check

Goal: Rule out chimney downdraft or glass doors blowing out the pilot.

  • A downdraft can blow out the pilot. Check that the chimney cap is intact and the flue is open.
  • If the fireplace has glass doors, some models require them to be open when lighting the pilot. Check your owner’s manual. Close doors after the pilot is established if the manual allows.
  • Good: Pilot remains steady. No flickering from draft.
  • Bad: Pilot flickers or goes out when wind blows—chimney or venting issue; call a technician.

When to get help

If you smell gas, evacuate immediately. Do not turn on lights or appliances. Call 911 or your gas utility from outside. Do not call a technician for an active gas leak—that is an emergency.

Call a technician if:

  • The pilot does not light at all (different problem—gas supply, orifice).
  • Cleaning and thermocouple replacement did not fix it.
  • The main burner lights but goes out (thermopile or gas valve).
  • You are not comfortable working with gas.

Verification

  • The pilot lights when you turn the knob and stays lit when you release it.
  • No gas smell. Pilot flame is strong and blue.
  • Main burner lights when you turn the fireplace on (if applicable).

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the fireplace lights but goes out when you release the knob or shortly after.
  2. Gas supply and pilot Check gas valve is on; confirm pilot flame is strong and blue.
  3. Thermocouple Check thermocouple is in the pilot flame; clean or replace if faulty.
  4. Pilot orifice and hold time Clear orifice if clogged; hold knob 30–60 seconds when lighting.
  5. Draft Check chimney cap, flue, and glass doors per owner's manual.
  6. Call a pro Gas smell—evacuate, call 911 or gas utility from outside. Repeated failures or gas valve—call a technician.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Whether the pilot lights at all
  • Whether the pilot is strong and blue or weak and yellow
  • Thermocouple position (in or out of flame)
  • Whether the orifice was clogged
  • Steps already tried

Does the fireplace light but go out when you release the knob or shortly after?

Turn to pilot, press and hold, light the pilot. Keep holding 30–60 seconds. Release. If the pilot dies when you release or within a few seconds, the fireplace will not stay lit.

Turn the control knob to pilot, press and hold, light the pilot. Hold for 30–60 seconds. Release. Good: pilot appears but goes out when you release—symptom confirmed. Bad: pilot does not light at all—different problem (gas supply, orifice); see gas path or call a technician.

Yes No

You can change your answer later.

Do you smell gas?

Gas smell indicates a leak. Evacuate immediately.

If you smell gas, do not turn on lights or appliances. Evacuate immediately. Call 911 or your gas utility from outside. Good: no gas smell—proceed. Bad: gas smell—evacuate, call 911 or gas utility from outside.

Yes No

You can change your answer later.

Is the gas supply valve on?

The valve handle parallel to the pipe means on; perpendicular means off.

Check the gas supply valve near the fireplace. Handle parallel to pipe = on. If closed, open it and wait a minute. Good: valve on—proceed to thermocouple. Bad: valve was off—open and retest.

Yes No

You can change your answer later.

Open gas valve and retest

Open the gas supply valve. Wait a minute for gas to reach the pilot. Light the pilot and hold for 30–60 seconds. If it stays lit, you are done. If not, proceed to thermocouple check.

Done

Is the thermocouple in the pilot flame and is the pilot strong?

The thermocouple must sit in the pilot flame tip. A weak or yellow pilot can cause the flame to go out.

Check the thermocouple—thin metal rod next to the pilot. It must sit in the flame tip. Gently bend it toward the flame if needed. Clean the tip with fine-grit sandpaper. Confirm the pilot is strong and blue. In flame and strong: proceed to hold time. Not in flame or weak: adjust and clean, then check pilot orifice for clog.

Yes No

You can change your answer later.

Adjust thermocouple and clean orifice, then test

Bend the thermocouple toward the pilot flame. Clean the tip. Turn off gas, clear the pilot orifice with a needle or compressed air—do not enlarge. Turn gas on, light the pilot, hold for 60 seconds. Release. If it stays lit, the fix worked. If not, replace the thermocouple or call a technician.

Done

Does the pilot stay lit after holding the knob 60 seconds?

Some fireplaces need a full minute for the thermocouple to heat.

Light the pilot. Hold the knob for a full 60 seconds. Release slowly. Stays lit: fix complete. Goes out: thermocouple may have failed—replace it or call a technician.

Yes No

You can change your answer later.

Replace thermocouple and test

Shut off the gas at the supply valve. Disconnect the thermocouple and replace with an exact match (match the part number). Restore gas and light the pilot. If it still goes out, check for downdraft or call a technician.

Done

Pilot stays lit

The fix worked. The pilot should stay lit when you release the knob.

Done

Call a technician

If you smell gas, evacuate immediately. Do not turn on lights or appliances. Call 911 or your gas utility from outside. Call a technician if: the pilot does not light at all; cleaning and thermocouple replacement did not fix it; the main burner lights but goes out (thermopile or gas valve); or you are not comfortable working with gas. Gas valve repairs always need a pro.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a gas fireplace light but not stay lit?
The thermocouple senses the pilot flame and keeps the gas valve open. If it does not sit in the flame, is dirty, or has failed, the valve closes and the pilot goes out. A weak pilot, clogged orifice, or chimney draft can also cause the flame to go out.
Can I fix a gas fireplace that will not stay lit myself?
Yes. You can check the thermocouple position, clean the pilot orifice, and replace the thermocouple if faulty. Gas valve repairs require a professional. Never work on gas lines yourself.
When should I call a technician for a gas fireplace that will not stay lit?
If you smell gas, evacuate and call 911 or your gas utility from outside. Call a technician if cleaning and thermocouple replacement do not fix it, if the pilot will not light at all, or if you are not comfortable working with gas.

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