Gas Water Heater Pilot Won’t Stay Lit? Causes and Safe Fixes

Quick answer: A gas water heater pilot usually won't stay lit because of a dirty or failed thermocouple, a clogged pilot, drafts, a blocked air intake, a gas supply problem or a failing gas control valve. Follow the lighting instructions on the tank label. If you smell gas, don't relight it. Leave the house and call 911 or your gas utility from outside. A pilot that keeps going out can also point to a venting problem, which is a safety concern. Book water heater repair and we'll find the cause.

No hot water in the morning, you go down to the basement, and the pilot is out again. Relighting works for a while, but a repeat problem means something needs fixing. Here's what's behind it, what you can safely check and when to call.

How the pilot system works

Older-style gas water heaters use a small, constant flame to light the main burner. Here's how the safety system works:

1. The pilot flame heats a metal sensor called a thermocouple.
2. Heat from the flame produces a tiny electrical signal.
3. That signal holds open a valve in the gas control.
4. If the flame goes out, the signal drops and the valve closes, so gas stops.

This is why a problem with the sensor shuts the whole heater down. It's working as designed.

Before you do anything: gas safety

If you smell gas (rotten eggs):

• Don't try to relight anything
• Don't operate switches or use phones inside
• Leave the house with everyone
• Call 911 or your gas utility from outside

Wait for a clear go-ahead before returning.

The most common causes

Dirty or failed thermocouple

This is the most common cause. Soot or age weakens the signal. The pilot lights but goes out when you release the knob, or it goes out at random. A technician can test it and replace it if needed.

Dirty pilot tube

Dust, lint and debris can clog the small pilot opening. You may see a weak, small or yellow flame that doesn't reach the thermocouple properly.

Drafts

Wind down a vent, a nearby window, a fan or an open door can blow out the flame, especially in basements, garages and closets. Stormy days are a common trigger at the shore.

Blocked air intake or flame arrestor

Many newer heaters have a sealed combustion chamber and a screen at the bottom that lets air in. Lint, dust and pet hair can clog it, starving the flame. Laundry rooms are especially prone to this.

Venting problems

If exhaust isn't leaving properly, the flame may go out, and combustion gases may spill into your home. Warning signs include:

• Rust or moisture at the top of the tank
• Soot or discoloration around the vent connection
• A blocked or disconnected vent pipe
• A chimney issue, especially after replacing other equipment

Treat this as urgent. Keep your CO alarms working. See carbon monoxide safety.

Gas supply

Other gas appliances out too? There may be a supply or valve issue. Check whether your stove or furnace still works, then call your gas utility if you suspect the problem is upstream.

Faulty gas control valve

If the thermocouple is good but the pilot still won't hold, the gas control may be at fault. It's a more significant repair, and replacing it on an older tank may not be worth it.

Electronic ignition problems

Many newer water heaters use a hot surface igniter or intermittent pilot, with no standing flame. Look for a blinking status light. These faults usually need a technician. Tankless units have their own error codes. See descaling a tankless water heater.

Safe checks you can do

1. Look at the label on the tank and find the lighting instructions.
2. Sniff for gas before you do anything. If you notice any gas smell, leave.
3. Check that the gas valve is on: the handle on the supply line should be in line with the pipe.
4. Check other gas appliances to see if they work.
5. Look for drafts from open windows, fans or vents.
6. Clear dust and lint from around the base, without opening any sealed compartment.
7. Follow the relighting instructions exactly, if your model is designed for it.

If the pilot goes out again, stop relighting it and call. Don't try to bypass any safety device, and don't open a sealed burner chamber.

What the pilot flame tells you

Why you shouldn't ignore a repeat problem

• Venting issues can bring carbon monoxide indoors
• Soot suggests poor combustion
• Worn safety parts should be replaced correctly
• Morning cold showers tend to keep happening until the cause is fixed

How we fix it

1. Check for gas leaks and test for carbon monoxide
2. Check gas supply and pressure
3. Inspect and clean the pilot and burner
4. Test the thermocouple or igniter
5. Test the gas control and thermostat
6. Check venting and the air intake
7. Confirm correct combustion and a good hot water supply
8. Give you an upfront price before any repair begins

Repair or replace?

A thermocouple or pilot cleaning is usually a straightforward repair. Consider replacing if:

• The heater is around 8 to 12 years old or older and needs a gas control
• The tank is leaking
• You're seeing rusty water or a lot of sediment
• It already doesn't make enough hot water

See water heater lifespan, what's included in a replacement and tankless vs tank.

How to prevent pilot problems

• Keep the area around the heater clean and clear
• Don't store chemicals, paint or gasoline near it
• Keep lint under control in laundry rooms
• Have venting checked as part of regular service
• Flush the tank as recommended (see flushing a water heater)
• Keep carbon monoxide alarms on every level and near bedrooms

Why does it go out at certain times?

Timing is a useful clue, so make a note of when it happens:

• On windy days: look at drafts and venting.
• When the dryer or an exhaust fan runs: strong fans can pull air and disturb the flame, especially in small utility rooms.
• After a gas utility outage or meter work: air in the line may need clearing.
• After a renovation: dust and new construction can clog the air intake.
• At random: the thermocouple or gas control may be failing.

Tell us the pattern when you call. It can save diagnostic time.

If you have to relight the pilot more than once, stop and book a visit.

Same day water heater repair near you

We repair and replace gas and electric water heaters of every brand, including Bradford White, Rheem and Navien, across all 153 towns in Ocean, Monmouth, Burlington and Middlesex counties. That includes Lakewood, Hazlet, Perth Amboy and Maple Shade.

No hot water? Book online or call (732) 779-7106 for same day service and an upfront price.