Your water heater pilot light keeps going out because the thermocouple, flame sensor, or gas valve is failing to confirm a flame - so the safety system shuts the gas off. The fix is usually a $15-$40 thermocouple replacement, a $150-$250 gas valve repair, or a $75-$150 cleaning of the pilot orifice. Below we walk through why it happens, how to relight it safely, and when to call us in Ohio.
We're OH Water Heater Repair, and we handle Water Heater Repair in Ohio every day - from 20-year-old tanks in Dayton basements to newer power-vent units in Delaware County. A pilot that won't stay lit is one of the most common calls we get, and it's almost always one of five things.
Why Does My Water Heater Pilot Light Keep Going Out?
A water heater pilot light keeps going out when the thermocouple stops generating enough millivolts to hold the gas valve open. The thermocouple is a small metal rod sitting in the pilot flame. It produces about 20-30 millivolts when hot; when that signal drops below roughly 10 mV, the gas valve closes and the pilot dies.
That's the mechanical answer. The practical answer is that one of five components has failed or drifted out of spec:
- Thermocouple - the most common culprit, especially on tanks 6+ years old.
- Pilot orifice - clogged with dust, rust, or spider webs, producing a weak yellow flame instead of a sharp blue one.
- Gas valve - the internal safety magnet or diaphragm has failed.
- Draft or venting issue - a backdraft blows the flame out.
- Air in the gas line - common after a utility shutoff or new install.
If your pilot dies within seconds of relighting, it's almost always the thermocouple or the gas valve. If it burns for hours or days and then quits, look at draft, venting, or a slow-building orifice clog.
How to Relight Your Water Heater Pilot Light Safely
Relighting a pilot light is safe if you follow the manufacturer's sequence and stop the moment you smell gas. Here's the standard procedure for most residential gas tanks:
- Turn the gas control knob to OFF and wait 5-10 minutes for any residual gas to clear.
- Remove the outer and inner burner access panels.
- Set the knob to PILOT. Press and hold it down.
- While holding, click the igniter button or hold a long lighter to the pilot tube.
- Keep holding the knob for 30-60 seconds after the flame lights, then release.
- If the flame stays lit, turn the knob to ON and replace the panels.
If the flame goes out the second you release the knob, the thermocouple isn't holding. Stop and call us - repeated relighting attempts waste gas and can damage the valve.
If you smell rotten eggs or hear hissing, leave the house and call your gas utility first. Then call us for Gas Water Heater Repair in Ohio once the utility clears the property.
Water Heater Pilot Light Troubleshooting: The 5 Most Common Causes
Water heater pilot light troubleshooting starts with the flame color and how long it survives. A healthy pilot burns blue with a slight yellow tip. A weak or dirty pilot burns mostly yellow and flickers.
1. Failed thermocouple
Thermocouples cost $10-$25 at any hardware store and take about 30 minutes to swap. On most tanks, the thermocouple sits behind the burner door and threads into the gas valve. If yours is original to a tank made before 2015, replace it - even if it tests borderline.
2. Clogged pilot orifice
The pilot orifice is a pinhole about the size of a pin tip. Dust, rust flakes, and spider egg sacs plug it in a season or two. We clean them with a soft brush and compressed air - never a wire, which reams the hole and changes the flame shape permanently.
3. Bad gas valve
When the thermocouple tests good but the pilot still won't hold, the gas valve's internal safety magnet has failed. This is a $150-$250 repair on most standard tanks, and on a tank older than 12 years, replacement usually makes more sense than repair.
4. Draft or venting problem
In Ohio, cold air rolling down a metal flue can snuff a pilot - especially on tanks installed against an exterior wall or in a garage. We see this most in older homes around Water Heater Repair in Johnstown, where short flues and tight mechanical closets are common. A draft hood or vent correction usually solves it.
5. Air in the gas line
If the utility shut off your gas for service, or you just had a new tank installed, the line may still have air in it. Purging the line takes 5-10 minutes of holding the pilot knob. If it won't purge after two attempts, call us.
Common Mistakes to Avoid When Your Pilot Light Goes Out
Homeowners cause more damage by rushing the relight than the pilot ever does on its own. Watch for these:
- Relighting without waiting 5-10 minutes. Residual gas can flash. This is the single most dangerous mistake.
- Holding the knob down for only 10 seconds. The thermocouple needs 30-60 seconds to reach operating temperature.
- Using a wire or paperclip to clean the orifice. You'll enlarge the hole and ruin the flame shape.
- Bypassing the thermocouple. Never jumper or tape a safety switch. It exists to shut off gas when there's no flame.
- Ignoring a yellow flame. A steady yellow pilot means incomplete combustion - a carbon monoxide risk, not just an inconvenience.
If your tank is 10+ years old and you're facing a $200+ repair, ask us about Water Heater Replacement in Ohio instead. A new 40-50 gallon gas tank runs $1,100-$1,800 installed in 2026, and it comes with a 6-12 year warranty.
When to Call a Professional
Call a licensed plumber when the pilot won't hold after two clean relight attempts, when you smell gas, or when the flame is yellow instead of blue. Those three signs point to a failed thermocouple, a bad gas valve, or a combustion problem - all of which we handle with parts on the truck.
We diagnose the pilot, test the thermocouple with a multimeter, inspect the venting, and confirm the flame is burning clean before we leave. If you're in Water Heater Repair in West Chester or anywhere in Southwest Ohio, we can usually be on-site the same day. If the tank is dead and you need hot water tonight, our Emergency Water Heater Repair in Ohio line runs 24/7.
Frequently Asked Questions
Why does my water heater pilot light keep going out?
In 8 out of 10 cases, a worn thermocouple stops sending the 20-30 millivolts needed to hold the gas valve open. Other causes: a clogged pilot orifice, a failed gas valve, or a draft blowing the flame out. A multimeter test confirms which one in about 10 minutes.
How do I fix a water heater pilot light that keeps going out?
First, replace the thermocouple - it's a $15-$40 part and the most common fix. If the pilot still dies, clean the orifice and check for drafts. If it still won't hold, the gas valve needs replacement, which is a job for a licensed plumber.
Is it safe to relight a water heater pilot light?
Yes, if you follow the manufacturer's sequence and wait 5-10 minutes with the gas off before relighting. Never relight if you smell gas, and never bypass the thermocouple. If the flame won't hold after two attempts, stop and call a professional.
Should I call a professional if my water heater pilot light keeps going out in Ohio?
Yes - if it dies twice in a row, if the flame is yellow, or if you smell gas. A licensed plumber can test the thermocouple, inspect the gas valve, and check venting in a single visit. Most repairs run $150-$350 in 2026.
How much does it cost to fix a pilot light that keeps going out?
Thermocouple replacement runs $150-$250 installed. Pilot orifice cleaning is $75-$150. Gas valve replacement is $250-$450. If the tank is 10+ years old, replacement at $1,100-$1,800 installed is often the better long-term call.
Get Help with Water Heater Repair in Ohio
If your pilot light won't stay lit and you've already tried a clean relight, we can diagnose and fix it today. Call OH Water Heater Repair at +1 614-543-4891 - we carry thermocouples, gas valves, and pilot assemblies on every truck.