Why is my gas fire igniting but won't stay on?

Author: Emmitt Nader  |  Last update: Tuesday, July 1, 2025

Your gas fireplace could be turning off for several reasons. The most like culprits are likely tied to some kind of problem with your setup. Anything from issues with your pilot light, clogged ports on burners, damage to heating components, and thermocouple/thermopile malfunctions can be to blame.

Why is my gas fire igniting but not staying on?

There are many possible reasons why the burner will not stay lit - the gas jet may be blocked, the valve may be set too low, the air flow may be restricted, there may be an issue with the pilot light, and so on.

How do you fix a gas fireplace that won't stay lit?

You need to replace the thermocouple and thermopile . Basically the thermocouple senses the flame and keeps the pilot lit and the thermopile produces the voltage to open the gas valve . If the pilot doesn't stay lit it's your thermocouple . You need to replace the thermocouple as cleaning usually doesn't work .

Why does my gas fireplace ignite then turn off?

Key Takeaways: Thermocouple issues, pilot light problems, blocked venting systems, safety features, and gas supply issues are common reasons why gas fireplaces shut off. Regular maintenance, cleaning, and professional servicing are essential to prevent unexpected shut-offs.

Why does the pilot light on my gas fire keep going out?

If your gas fireplace pilot light keeps going out, you may have a problem with faulty pilot controls. The pilot control failing due to age or a mechanical issue can cause your pilot light to keep going out and prevent it from being relit.

Gas Logs: Flame Won't Stay On - Why?

How do you fix a pilot light that keeps going out?

How To Re-Light A Furnace Pilot Light ?
  1. Step 1: Review Furnace Manual. ...
  2. Step 2: Identify Pilot Light. ...
  3. Step 3: Turn OFF Gas. ...
  4. Step 4: WAIT 5 Minutes, then Turn Gas to "Pilot" ...
  5. Step 5: Hold Reset Button. ...
  6. Step 6: Press The Igniter While Holding The Reset Button. ...
  7. Step 7: Turn Gas to "ON" position.

How do I know if my thermocouple is bad on my gas fireplace?

Common Signs of a Failing Thermocouple

Here are some common indicators: Difficulty Lighting the Fireplace: If you struggle to light your fireplace, or if it takes several tries to keep the pilot lit, it could suggest that the thermocouple is not sensing the flame correctly and is failing to keep the gas supply open.

Why does my gas stove fire keep going out?

Poor ventilation can affect the flame as the vents become dirty or blocked, preventing sufficient airflow. It can disrupt the balance of oxygen and pressure needed for stable combustion, activate safety mechanisms, and lead to incomplete combustion and overheating, all of which can cause a gas fire to go out.

How much to replace a thermocouple in a gas fireplace?

Fireplace thermocouple replacement costs $150 to $350 total.

Why won t my fireplace fire stay lit?

Firewood won't stay lit if it's made from softwood. Hardwoods include oak, birch, beech and maple, all dense enough to keep uncannily hot fires going for many hours. Oak is the densest of the hardwoods, generating the most heat for the longest time.

Why wont my pilot light stay lit when I release the knob?

The flame will go out if you release the knob before it is hot. The thermocouple can become dirty and caked with grit, preventing it from heating up and detecting that the pilot is lit. As a result, the pilot will always go out after you release the reset button.

Is a gas fireplace supposed to stay lit?

A: Yes, turning off the pilot light when the fireplace isn't in use, such as during the warmer months, can help save energy and reduce your gas bill.

Why is my gas flame not staying on?

The most common cause of this is dirty or blocked burners, which is the part that you can easily take off to clean.

How do I know if my gas fireplace igniter is bad?

Gas Fireplace Igniter Isn't Sparking

If your pilot is lit and the fireplace isn't igniting when you push the button or flip the switch, the igniter may be dirty or defective.

Can I replace a thermocouple myself?

Here at Boss Plumbing, we highly recommend you not try to replace the thermocouple on your water heater yourself. Though not a highly complex water heater repair, it nevertheless does involve the use of gas. Thus, if you are unsure about what you are doing, one small mistake could lead to a disaster.

Why won't my gas fireplace stay lit?

Your gas fireplace could be turning off for several reasons. The most like culprits are likely tied to some kind of problem with your setup. Anything from issues with your pilot light, clogged ports on burners, damage to heating components, and thermocouple/thermopile malfunctions can be to blame.

How to tell if a thermocouple is bad?

There's really just one telltale sign of letting you know when the thermocouple isn't working, and that's when the pilot light won't stay lit. If you experience this problem, it's important to have your thermocouple assessed as soon as possible.

Why does my gas fire keep turning itself off?

Thermocouple and Thermopile Issues

They generate a small amount of electricity when heated by the pilot flame, signaling that the pilot light is lit and allowing the gas valve to open. Over time, these components can get dirty or fail, causing the gas fireplace to shut off abruptly or prevent it from staying lit.

Why does my gas burner shut off after ignition?

Flame Sensor Problems

If the heat is at the appropriate level, the sensor will trigger the furnace's control board to blow warm air into the combustion chamber to complete the heating cycle. If a furnace's main burner shuts off after ignition, it could be due to dirt, dust, and other debris covering the flame sensor.

Is it hard to replace a thermocouple on a gas fireplace?

Thermocouples are designed to detect a pilot light's loss of heat and close the gas valve to prevent a gas leak. Replacing a thermocouple is a relatively easy fix that can take less than two hours.

Will pilot light if thermocouple bad?

Nothing lasts forever, and when the thermocouple wears out, the pilot won't stay lit and your appliance won't work. The pilot can go out for a number of other reasons, however, so if you're having trouble getting the pilot to stay lit, the thermocouple may not be at fault.

What are the signs of a bad thermopile?

Symptoms Pilot won't light. Pilot lights but burner won't. System lights, but goes out after a while.

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