A pilot light that goes out frequently is almost always caused by a faulty safety sensor, airflow issues, or gas supply problems. The flame needs to stay steady and hot enough to keep the gas valve safely open.
If your pilot light keeps going out, there's a chance that the gas supply has been compromised. A pilot light needs gas to continue burning—so if there's no gas, then there's no pilot light. Check the gas valve; there's a high chance it's dirty or malfunctioning.
To get your pilot light to stay lit, you must hold down the gas/reset button for 30–60 seconds after the flame appears. If you let go too soon, the safety sensor won't detect the heat and will shut the gas off. If it still goes out, the thermocouple, gas valve, or airflow needs attention.
It's sometimes called the “flame sensor.” It shuts the gas off if the pilot goes out. Gas that flows through your furnace could enter your house if the thermocouple fails to turn it off. Protecting your home from gas buildup is the thermocouple.
There are several reasons why your water heater pilot light keeps going out: Thermocouple issues: If the thermocouple is faulty or dirty, it can be the reason why does the pilot light go out on water heater. Drafts: Strong drafts can blow out the pilot light. This is common in basements or poorly ventilated areas.
Pilot Light Issues: The pilot light may go out due to a blocked or damaged thermocouple. Relighting is typically inexpensive unless the thermocouple requires replacement, which can range between $120 and $300.
Common Signs of a Bad Furnace Thermocouple
Yes, if a pilot light goes out, you will often smell a faint or noticeable odor. Natural gas is naturally odorless, but utility companies add a distinct chemical called mercaptan, which smells like rotten eggs or sulfur, so you can easily detect it.
Cleaning a gas fireplace thermocouple is a simple maintenance task that fixes pilot lights that won't stay lit. Turn off the gas and let the unit fully cool. Remove the glass and logs to access the pilot assembly. Gently scrub the thermocouple rod with high-grit sandpaper or emery cloth, wipe away debris, and reassemble.
A frozen pipes furnace failure can cause major problems inside your home. Ice builds up fast in unheated spaces, and when frozen water expands, it can burst pipes wide open. That kind of mess is the last thing anyone wants during a winter heating outage.
1. The pilot light won't stay lit. The main issues that keep a pilot light from staying lit are a dirty or damaged thermocouple, a clogged or damaged gas tube, or a faulty pilot control knob. If the thermocouple is damaged or dirty, it won't keep the valve open.
A gas furnace often shuts off if the flame sensor is dirty or faulty. Another common cause is overheating, which triggers the high limit switch to shut it down for safety. Sometimes, clogged air filters can restrict airflow and cause the same issue.
If your pilot light won’t stay lit, the most common culprit is a dirty or faulty thermocouple (the small metal rod next to the flame that signals the gas valve to stay open). To fix it: hold the gas knob down longer, clean or replace the thermocouple, or clear a blocked pilot tube.
A well-functioning pilot light should ideally stay lit indefinitely. However, if it goes out more than once or twice a year, it usually points to a mechanical or environmental issue rather than normal operation.
Here are the most common indicators that your gas valve might be failing:
Thermocouple Lifespan
A thermocouple usually lasts 3-5 years on a regularly used standing-pilot system. Some last longer, but once they begin to weaken you'll see the classic symptom: the pilot won't stay lit unless you hold the knob.
Steps for Furnace Thermocouple Cleaning
Yes, replacing a thermocouple is an accessible DIY project. It typically takes under an hour using basic tools (like an adjustable wrench), and replacement parts are inexpensive. The most important step is safely shutting off the gas supply and ensuring there are no leaks once reassembled.
[4,5] In the case of low levels of exposure (0.05 ppm), early signs and symptoms include the smell of rotten eggs, fatigue, headaches, nausea or vomiting, dizziness or lightheadedness, and poor memory and concentration.
In most cases, it's not a direct safety risk because modern water heaters have safety features like thermocouples, which shut off the gas supply if the pilot light goes out. This prevents gas from leaking into your home, reducing the risk of a gas buildup.
Yes, a pilot light can cause carbon monoxide. Because it burns fossil fuels (like natural gas or propane), carbon monoxide is produced as a byproduct of combustion. While a properly adjusted and ventilated flame is usually not dangerous, problems arise if the system malfunctions.
The part is rather small and inexpensive, but replacing it requires the expertise of a professional plumber for safety reasons. Having a thermocouple replaced usually costs $125-200, while the part itself is about $15-25.
If the thermocouple is bad, the pilot light will not stay lit. While you can manually light the pilot by holding down the gas valve, the flame will extinguish the moment you release it because the faulty thermocouple cannot detect the heat and signal the gas valve to stay open.