How to Fix Water Heater Pilot Light

If your gas water heater has no hot water and you can't see a flame through the small viewing window at the bottom of the tank, the pilot light is out. This is one of the most common gas water heater problems — and in most cases, you can fix it yourself in just a few minutes.

This guide covers why the pilot light goes out and how to fix it, including what to do when it won't stay lit.

Why Did My Pilot Light Go Out?

The most common reasons a pilot light goes out include:

• A draft or gust of air blew it out
• The thermocouple is faulty or dirty
• The gas supply was interrupted
• The gas valve is defective
• The pilot orifice is clogged

How to Relight the Pilot Light

Most gas water heaters have relighting instructions printed on a label on the front of the unit. Follow those instructions first. Here is the general process:

1. Turn the gas control knob to OFF and wait 5 minutes for any residual gas to clear
2. Turn the knob to PILOT
3. Press and hold the pilot button (or gas control knob) down to allow gas to flow to the pilot
4. While holding the button, use a long lighter or igniter to light the pilot flame
5. Continue holding the button for 30–60 seconds after the flame lights — this heats the thermocouple
6. Slowly release the button. If the flame stays lit, turn the knob to your desired temperature setting
7. If the flame goes out, wait 5 minutes and try again

Note: If the pilot won't light after 2–3 attempts, or if it lights but won't stay lit, there is an underlying problem that needs to be fixed.

Pilot Light Won't Stay Lit: Most Likely Cause

If the pilot lights but goes out as soon as you release the button, the thermocouple is almost certainly the problem.

The thermocouple is a safety sensor that detects whether the pilot flame is burning. When it senses heat from the flame, it sends a small electrical signal to keep the gas valve open. If the thermocouple is faulty, dirty, or not positioned correctly in the flame, it won't send that signal — and the gas valve closes, extinguishing the pilot.

How to Fix a Faulty Thermocouple

Option 1: Clean the thermocouple tip

Sometimes the thermocouple tip is coated with residue that prevents it from sensing heat properly. Use fine steel wool or sandpaper to gently clean the tip, then try relighting.

Option 2: Reposition the thermocouple

The thermocouple tip must be directly in the pilot flame. If it has shifted out of position, bend it gently back so the tip sits in the flame.

Option 3: Replace the thermocouple

If cleaning and repositioning don't work, the thermocouple needs to be replaced. This is an inexpensive and straightforward DIY repair.

💡 Recommended Part: Resideo CQ100A1013/U 24-Inch Replacement Thermocouple — fits most gas furnaces, boilers, and water heaters. Universal fit, easy to install.

How to replace the thermocouple:

1. Turn the gas control knob to OFF
2. Locate the thermocouple — it's the thin copper tube running from the pilot assembly to the gas valve
3. Unscrew the thermocouple from the gas valve (usually hand-tight or one wrench turn)
4. Pull the other end out of the pilot bracket
5. Insert the new thermocouple into the pilot bracket and screw the other end into the gas valve
6. Relight the pilot and test

Pilot Light Won't Light At All

If you can't get the pilot to light even with a flame source:

• Check the gas supply — make sure the gas valve on the supply line is open (handle parallel to pipe = open) and other gas appliances are working
• Check for a clogged pilot orifice — the tiny hole that lets gas through to the pilot can get clogged with debris. A professional can clean or replace it
• Check the gas valve — if gas isn't reaching the pilot at all, the gas valve may be defective

💡 Recommended Part: Gas Valve 70000 BTU — replacement gas valve for residential water heaters, 1/2" inlet size.

When to Call a Professional

Call a licensed plumber or gas technician if:

• You smell gas and the pilot won't light — leave the house and call your gas company immediately
• The pilot lights but the main burner won't ignite
• The gas valve needs replacement
• You're not comfortable working with gas appliances

Summary

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