Why Your Water Heater Pilot Light Keeps Going Out (and How to Fix It)
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Why Your Water Heater Pilot Light Keeps Going Out (and How to Fix It)
Gas water heater pilot light won't stay lit? The 5 most common causes — from a bad thermocouple to venting problems — and when to call a plumber.
A pilot that won't stay lit is most often a worn thermocouple or flame sensor. Other causes are a dirty pilot tube, a clogged air intake screen, venting problems or a failing gas control valve. Most are fixed in one visit.
If your gas water heater's pilot light keeps going out, you'll know it by the cold shower. The good news: this is one of the most fixable water heater problems.
Safety first: If you smell gas, don't relight anything. Leave the house and call the gas company from outside.
1. A worn-out thermocouple or flame sensor
The thermocouple is a small metal rod that sits in the pilot flame. It tells the gas valve "the pilot is lit, keep the gas on." When it wears out, it can't sense the flame, and the valve shuts the gas off. It's the single most common reason a pilot won't stay lit.
Fix: Replace the thermocouple (or thermopile/flame sensor on newer units).
2. A dirty pilot tube
Dust, lint and debris can clog the tiny pilot opening. A weak, yellow or flickering flame doesn't heat the thermocouple enough.
Fix: Clean the pilot assembly. A healthy pilot flame is steady and mostly blue.
3. Drafts or poor combustion air
Basement drafts — from a window, dryer vent or furnace area — can blow a small flame out. Newer heaters have a flammable vapor sensor and sealed combustion chamber that can trip if the air intake screen is clogged with lint.
Fix: Clean the intake screen and find the draft source.
4. Venting problems
If exhaust can't leave through the flue, many heaters shut themselves off to protect you from carbon monoxide. A blocked, disconnected or poorly sloped vent is a safety issue.
Fix: Have the venting inspected. Never ignore a heater that shuts down on its own.
5. A failing gas control valve
If the thermocouple is new and the pilot still won't stay lit, the gas valve itself may be the problem.
Fix: Replace the gas control valve. On an older heater, this is often the point where replacement makes more sense.
How to relight a pilot safely
Every heater has relighting steps printed on its label — follow those first. In general:
- Turn the gas control knob to Off and wait at least 5 minutes for gas to clear.
- Turn the knob to Pilot, press and hold it, and press the igniter until the pilot lights.
- Keep holding the knob for 30–60 seconds, then release. The pilot should stay lit.
- Turn the knob to On and set the temperature.
If you smell gas at any point, stop, leave the house and call the gas company from outside. If the pilot won't stay lit after one or two tries, it's time for a repair.
When to call a plumber
Call ExpertPipe Rooter at (216) 203-6563 if:
- The pilot goes out again after relighting per the label
- The heater shuts itself off repeatedly
- You see soot, scorch marks or a yellow flame
- You smell gas — leave the house and call the gas company first
We serve Cleveland's west side and western suburbs, including Lakewood, Parma, Westlake, Rocky River and North Olmsted.
Frequently asked questions
Why does my pilot light go out but relights fine?
A pilot that lights but won't stay lit usually points to a weak or failing thermocouple that can't keep the gas valve open. It's one of the most common and simplest water heater repairs.
Is it safe to keep relighting a water heater pilot?
Relighting once following the label instructions is fine. If it keeps going out, stop and have it checked — repeated shutdowns can signal a venting or gas valve problem.
How long does a thermocouple replacement take?
Typically under an hour on a standard gas water heater, including testing the flame and venting afterward.
Keep reading
Related guides
Water Heater Repair or Replace? A Simple Guide for Cleveland Homeowners
Repair makes sense on a heater under about 8 years old with a dry tank and a failed part like a thermocouple, gas valve, element or relief valve.
Read the guide →Why Your Water Heater Makes Popping or Banging Noises
Popping or rumbling is almost always sediment on the bottom of the tank trapping water that boils through.
Read the guide →Why Does My Hot Water Run Out So Fast? 6 Causes in Cleveland Homes
Hot water usually runs out fast because of sediment in the tank, a broken dip tube, a failed element (electric) or burner problem (gas), or a heater that's too small for the household.
Read the guide →Talk to a local plumber
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