Pilot Light Keeps Going Out? What It Means

If you've relit your pilot light more than twice this month, something isn't right. A healthy boiler shouldn't need this. It's a small blue flame doing a big job, and when it keeps dying on you, it's usually trying to tell you something about the boiler underneath it.

Most modern combi and system boilers don't have a traditional pilot light at all, they use electronic ignition instead. So if you've got one that goes out repeatedly, you're likely dealing with an older heat-only or regular boiler. That's worth knowing on its own, because older boilers are more prone to the faults below, and at some point repairing them stops making financial sense.

The usual suspects

A pilot light that won't stay lit is almost always one of these:

• A faulty thermocouple. This small safety sensor detects the pilot flame and keeps the gas valve open. When it wears out, it cuts the gas supply even though the flame is fine, and the light goes out.
• A dirty or blocked pilot jet. Dust and debris can restrict the tiny gas opening, causing a weak, unstable flame that's easily extinguished.
• Draughts. If the boiler casing has come loose or a nearby vent is blowing into the burner compartment, that's often enough to snuff out a small flame.
• A failing gas valve. Less common, but it can stop gas flowing consistently to the pilot assembly.
• Condensation or damp inside the boiler, particularly in older units without good ventilation.

Is it dangerous?

Not usually, but it's not something to keep ignoring either. Relighting a pilot repeatedly on your own is fine if you know the manufacturer's steps, but if it goes out constantly, there may be an underlying fault that a Gas Safe registered engineer needs to look at properly. Never attempt to bypass a safety cut-out yourself. The Gas Safe Register has good guidance on what's safe for homeowners to do and what isn't.

When it's a sign of something bigger

If your boiler is over ten years old and the pilot issue keeps recurring, that's often the point where repair costs start rivalling replacement costs. It's worth reading our guide on signs you need a new boiler to see how this fits the bigger picture. A persistent pilot fault paired with rising energy bills, as noted by the Energy Saving Trust, is a common tipping point for homeowners deciding to upgrade rather than keep patching an old system.

What to do next

• Check the manufacturer's manual for correct relighting steps first.
• If it goes out again within a day or two, stop relighting it and book a service. Our servicing page covers what's included and how regular check-ups catch these faults early, and our guide on how often a boiler should be serviced explains the recommended intervals.
• If the engineer says the fix costs more than it's worth, compare that against a new unit. Our new boiler cost guide breaks down realistic pricing, and combi vs system vs regular boilers explains why most replacements move to electronic ignition anyway.

Get it sorted properly

A flickering, dying pilot light is annoying, but it's also useful information. It tells you the boiler is ageing and needs either a proper repair or a replacement plan. If you're in the Midlands and want a straight answer on which one makes sense, get a fixed price from a Gas Safe registered engineer, or if it's gone out completely and you've no heating tonight, use our emergency help line instead.