Troubleshooting guide
Pilot lights, then goes out (or won't stay lit)
If the pilot lights but drops out after a few seconds, the fireplace's safety system is doing its job: it shuts the gas off when it can't prove there's a flame.
Why it happens
On a standing-pilot (millivolt) fireplace, a thermocouple sits in the pilot flame. When it's hot it makes a tiny voltage that holds the gas valve open. If the flame isn't hitting it properly, or the thermocouple is worn out, the valve closes and the pilot goes out. Electronic-ignition models use a flame sensor that works on a similar "prove the flame" idea.
The manufacturer guides list the same short set of causes:
- A weak or misdirected pilot flame that doesn't wrap the top of the thermocouple (Napoleon's diagrams show the flame enveloping the top 3/8"–1/2").
- A worn-out thermocouple producing too little voltage.
- A loose thermocouple connection at the gas valve or interrupter block.
- Low gas pressure.
- On sealed direct-vent units, a venting problem such as a blocked or iced-over vent cap.
Safe things you can check
- Hold the knob long enough. On standing-pilot units, the lighting instructions usually say to keep the knob pressed for a set time after the pilot lights, so the thermocouple can heat up. Follow your label exactly.
- Look at the pilot flame. It should be steady and wrap the tip of the thermocouple or sensor. A small, lazy or yellow flame, or one that flickers away from the sensor, is worth showing to a tech.
- Check outside. Make sure the vent cap on the outside wall or roof isn't blocked by snow, ice, leaves or a nest.
- Batteries. On battery-powered systems (like Valor's GV60), weak receiver batteries can keep the system from holding.
Leave these to a tech
Cleaning or adjusting the pilot assembly, testing millivolts, tightening the thermocouple at the valve (manufacturers warn that over-tightening damages the valve's electromagnet) and checking gas pressure need the right tools and know-how. A video call can tell you which of these it is before anyone orders parts. See thermocouple vs. thermopile for what the tests mean.
Common questions
Why does my fireplace pilot light go out when I let go of the knob?
The thermocouple isn't producing enough voltage to hold the gas valve open. Usually the pilot flame isn't heating it properly, the thermocouple is worn, or its connection at the valve is loose. Make sure you're holding the knob for the time your lighting instructions say.
Is it dangerous if my pilot light keeps going out?
The pilot going out is the safety system working: it shuts off gas when there's no flame. But if you ever smell gas, leave the home and call your gas utility or 911 from outside.
Does a pilot that keeps going out mean I need a new thermocouple?
Often, but not always. A dirty pilot, a weak flame, a loose connection, low gas pressure or a venting problem can cause the same symptom. Testing the millivolt output tells you for sure before you buy a part.
Related guides
Thermocouple vs. thermopile
Two small parts that cause a lot of no-heat calls, and how techs test them.
Read the guidePilot won't light
Clicking but no flame, or no spark at all. The usual causes, in order.
Read the guidePilot is lit, burner won't come on
The pilot's burning but the main flame never comes up.
Read the guideValor fireplace beeping
Rapid beeps, one long beep, one beep and no motor: Valor's own guide.
Read the guideSources
- Napoleon GSS48E/GSS48STE installation & operation manual (W415-3006): control module operation and troubleshooting
- Valor (Miles Industries) Troubleshooting Handbook, Oct 2025 (GV60 control system)
- Empire Comfort Systems service manual: thermocouples, thermopiles and millivolt testing
Brand names belong to their owners. Fireplace Helpline isn't affiliated with or endorsed by any manufacturer. Steps and codes vary by model and year, so always check your own owner's manual.