Why the Boiler Pilot Light Keeps Going Out

Written by Jennifer Aube
on Jan 27, 2010

To ensure our content is always up-to-date with current information, best practices, and professional advice, articles are routinely reviewed by industry experts with years of hands-on experience.

Reviewed by
H.R. Helm
on Jan 04, 2022

If you find that your boiler pilot light keeps going out and will not stay on, there are several things you can check and fix. Below is a list of reasons why this may be happening to your boiler.

1. Pilot Is Dirty

Your pilot light may be going out because it is simply dirty and filled with soot. Soot usually collects on the thermocouple. To restore the dirty thermocouple and pilot, take out a rag and a little warm soapy water and give it a good clean. You can use Q-tips to get around the little edges and corners.

2. Thermocouple Is Old

An old thermocouple may malfunction because it is worn out and needs to be replaced. This will cause your pilot light to go out.

3. Gas Valve Problems

The gas valve may be worn or malfunctioning. Check it and replace it if necessary. This should be replaced by a certified HVAC contractor that is familiar with your type of boiler.

4. Seal Is Not Sealed

Check the seals. If they are no longer forming a complete seal, you may want to replace them.

5. Overheat Switch

Many boilers have a switch that detects overheating. Check the switch to see if it is tripping. The thermostat may be a problem causing this to occur.