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Fix a gas fireplace that will not light

We'll rule out gas smell first, then help you check gas supply, pilot light, thermocouple, pilot orifice, and igniter—or tell you when to call a pro.

Troubleshooting · Home appliances
10–30 min
What you'll need
  • Owner's manual (for control knob and pilot location)
Step 1 of 8

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Steps

Goal: Rule out gas smell, then fix a gas fireplace that will not light.

  • Step back and sniff. If you smell gas, evacuate and call 911 or your gas utility from outside. Do not troubleshoot.
  • Check the gas supply valve and control knob. Gas valve handle parallel to pipe = on. Control knob set to Pilot or On per your owner’s manual.
  • Good: No gas smell and gas is on. Proceed to Gas supply and pilot.
  • Bad: You smell gas—evacuate. Gas off—open valve or replace propane, retest.

Gas smell check

Goal: Confirm there is no gas leak before troubleshooting.

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

Gas supply and pilot

Goal: Check gas supply and confirm the pilot is lit.

  • Confirm the gas supply valve is on (handle parallel to pipe for natural gas; propane tank valve open and tank has fuel).
  • Look at the pilot area. If the pilot light is lit, turn the control knob to On—the main burner should light.
  • Good: Pilot is lit and main burner lights when you turn to On.
  • Bad: Pilot is out—call a pro. Do not attempt to restore the pilot yourself. Pilot goes out or will not light—thermocouple or pilot orifice; call a pro. See Thermocouple and orifice.

Thermocouple and orifice

Goal: Understand when to call a pro for pilot, thermocouple, or orifice issues.

  • If the pilot is out or will not stay lit, the thermocouple or pilot orifice may have failed. Call a pro for thermocouple cleaning, alignment, or replacement, and for pilot orifice cleaning. Do not attempt to restore the pilot yourself.
  • If the piezo igniter does not spark, a pro can replace it or restore the pilot.
  • Good: Pilot is lit (by a pro) and main burner lights when you turn to On.
  • Bad: Pilot still out or will not stay lit—call a pro. Igniter glows but no flame—gas valve failed; call a pro. Do not work on gas valves yourself.

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 troubleshoot an active gas leak.

Call a pro if:

  • The pilot will not stay lit after cleaning or replacing the thermocouple.
  • The igniter glows but no flame appears (gas valve issue).
  • The pilot stays lit but the main burner does not light when you turn to On.
  • You are not comfortable working with gas.

Never work on gas valves or gas lines yourself.

Verification

  • Pilot light is lit and stays lit.
  • Main burner lights when you turn the control from Pilot to On.
  • No gas odor. No hissing from connections.
  • Flames are steady and blue (yellow tips may indicate a problem—check the owner’s manual).

Escalation ladder

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

  1. Gas smell check If you smell gas, evacuate and call 911 or gas utility from outside.
  2. Gas supply and control Check gas valve on, control knob set to Pilot or On.
  3. Confirm pilot is lit Confirm pilot is lit; if out, call a pro—do not restore it yourself.
  4. Thermocouple and orifice Call a pro for thermocouple or pilot orifice service.
  5. Call a pro Gas smell—evacuate, call 911. Pilot won't stay lit after thermocouple replacement, or igniter glows but no flame—call a pro.

What to capture if you need help

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

  • Whether gas supply is on (natural gas or propane)
  • Whether pilot lights and stays lit
  • Thermocouple condition (dirty, misaligned, continuity)
  • Whether pilot orifice is clear
  • Steps already tried

Do you smell gas?

Before any troubleshooting, step back and sniff. Gas has a rotten egg odor. If you smell it, evacuate and call 911 or your gas utility from outside.

Step back and sniff. Good: No gas smell—proceed to check gas supply. Bad: You smell gas—evacuate immediately. Do not turn anything on or off. Call 911 or your gas utility from outside. Do not troubleshoot.

Yes No

You can change your answer later.

Evacuate and call 911

Evacuate everyone from the area. Do not turn on lights or appliances. Call 911 or your gas utility from outside. Do not return until the leak is resolved.

Done

Is the gas supply on?

Gas valve handle parallel to pipe = on. For propane, check tank valve and fuel level.

Check the gas supply valve. Handle parallel to the pipe = on. For propane, confirm the tank valve is open and the tank has fuel. Good: gas on. Bad: valve closed or tank empty—open valve or replace tank, wait a minute, retest.

Yes No

You can change your answer later.

Open gas valve or replace propane, retest

Open the gas valve fully (counterclockwise) or replace the propane tank if empty. Wait a minute for gas to reach the fireplace. Check if the pilot is lit. If the pilot is out, call a pro—do not attempt to restore it yourself. If the pilot is lit, turn to On and the main burner should light.

Done

Is the pilot lit?

Look at the pilot area. The pilot is a small blue flame. If it is out, call a pro—do not attempt to restore it yourself.

Look at the pilot area (often behind the lower grille or in the firebox). Pilot is lit: turn the control to On and proceed to main burner. Pilot is out: call a pro—do not attempt to restore the pilot yourself. Pilot goes out or will not stay lit: thermocouple or pilot orifice issue; call a pro.

Yes No

You can change your answer later.

Does the main burner light when you turn to On?

Once the pilot is lit, turn the control from Pilot to On.

Turn the control knob from Pilot to On. Good: main burner lights. Bad: pilot stays lit but main burner does not light—gas valve or main burner orifice has failed; call a pro. Do not work on gas valves yourself.
Question

Does the main burner light?

Continue

You can change your answer later.

Is the thermocouple in the flame and the pilot orifice clear?

Thermocouple tip must sit in the pilot flame. Pilot orifice can be clogged by spiders or debris.

If the pilot is out or will not stay lit, the thermocouple or pilot orifice may have failed. Call a pro for thermocouple cleaning, alignment, or replacement, and for pilot orifice cleaning. Do not attempt to restore the pilot yourself. Good: pilot is lit (by a pro) and main burner lights. Bad: pilot still out or will not stay lit—call a pro. Igniter glows but no flame—gas valve; call a pro.
Question

Is the thermocouple good and orifice clear?

Continue

You can change your answer later.

Call a pro

If you smell gas, evacuate and call 911 or your gas utility from outside. Call a pro if: the pilot will not stay lit after cleaning or replacing the thermocouple; the igniter glows but no flame (gas valve); or you are not comfortable working with gas. Never work on gas valves or gas lines yourself.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a gas fireplace not light?
Common causes: gas supply off, pilot light out, faulty thermocouple, clogged pilot orifice, or failed igniter. The pilot must be lit before the main burner will light. Check gas supply and pilot first, then the thermocouple. If the igniter glows but no flame appears, the gas valve has failed—call a pro.
Can I fix a gas fireplace that will not light myself?
Yes, you can check the gas supply and control knob. If the pilot is lit, you can turn to On and the main burner should light. Thermocouple and pilot orifice work require a professional—do not attempt to restore the pilot yourself. Gas valve work always requires a pro.
When should I call a pro for a gas fireplace that will not light?
If you smell gas, evacuate and call 911 or your gas utility from outside. Call a pro if the pilot will not stay lit after replacing the thermocouple, the igniter glows but no flame appears (gas valve), or you are not comfortable working with gas.

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