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Generic Water Heaters Water Heater Pilot Light Won't Stay Lit: How to Fix It Yourself

A pilot light that lights but goes out as soon as you release the button is almost always a bad thermocouple. The thermocouple is a safety sensor that sits in the pilot flame. When it wears out, it cannot tell the gas valve that the pilot is lit, so the valve shuts off the gas. Replacing a thermocouple is one of the most common and affordable water heater repairs.

⚡ Difficulty: Medium⏱ 20-45 minutes💰 Parts cost: $0–$15🔧 Tools: Long-reach lighter, Fine-grit sandpaper or emery cloth, Wrench (small adjustable), Compressed air can (optional)

⚠️ Safety First

  • If you smell a strong gas odor (like rotten eggs), do not try to light anything. Leave the house and call the gas company from outside.
  • Wait a full 5 minutes after turning gas to Off before attempting to relight the pilot.
  • Work in a well-ventilated area. Open a window or door near the water heater.
  • Never force the gas control knob — if it does not turn, it may be in a lockout state.

Parts You May Need

Universal Thermocouple

~$8–$12

AmazoneBay

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Step-by-Step Repair

  1. 1

    Try relighting the pilot properly

    Turn the gas knob to Off and wait 5 minutes. Turn it to Pilot, press and hold it down firmly, and light the pilot with a long-reach lighter. Hold the knob down for a full 60 seconds — many people let go too soon. Count it out. Then slowly release. If the pilot stays lit, turn the knob to On. If it goes out, the thermocouple needs attention.

  2. 2

    Clean the thermocouple tip

    Turn the gas to Off. Locate the thermocouple — it is the thin copper tube running from the gas valve to the pilot assembly. The tip sits right in the pilot flame. Gently sand the tip with fine-grit sandpaper or emery cloth to remove any soot or oxidation. Also make sure the tip is positioned so the pilot flame directly hits it. If it has been bent away, gently bend it back into the flame.

  3. 3

    Clean the pilot tube

    While you are in there, check the pilot tube opening. If the pilot flame is weak or yellow instead of a crisp blue, the pilot tube may be partially clogged with dust or spider webs. Use compressed air to gently blow out the tube. A stronger pilot flame means a hotter thermocouple, which helps it work better.

  4. 4

    Replace the thermocouple if cleaning did not work

    Disconnect the thermocouple from the gas control valve — it threads off with a small wrench (usually 7/16 inch). Remove the tip from its bracket near the pilot. Install the new thermocouple with the tip positioned in the pilot flame. Reconnect it to the gas valve hand-tight plus a quarter turn with the wrench. Do not overtighten.

  5. 5

    Relight and confirm

    Follow the relighting procedure: Off, wait 5 minutes, Pilot, hold, light, hold 60 seconds, release. The pilot should now stay lit. Turn the knob to On and listen for the main burner to fire. Check back in an hour to make sure the pilot is still going strong.

If That Didn't Work

  • Strong drafts near the water heater blowing the pilot out
  • Faulty gas control valve (will not hold open even with a good thermocouple)
  • Partially closed gas supply valve reducing gas flow
  • Dirty or clogged main burner orifice

When to Call a Professional

If a new thermocouple does not fix the problem, the gas control valve itself may be faulty. Replacing a gas valve involves working with gas lines and should be done by a licensed plumber. If the water heater is more than 10 years old, consider replacing the entire unit rather than investing in expensive repairs.

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Disclaimer: This guide is for informational and educational purposes only and does not constitute professional repair advice. All repairs are performed at your own risk. RepairItFree.com is not liable for any personal injury, property damage, device damage, voided warranties, or other losses resulting from the use of this information.

If you are unsure about any step — especially anything involving electricity, gas, water, or refrigerant — stop and consult a qualified professional. Your safety is more important than saving money.

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