How to Reset Your Boiler Safely

When (and why) you should reset your boiler

Most modern combi, system and heat-only boilers have a built-in safety feature called a lockout. When the boiler detects a problem it cannot start or run safely with — for example a failed ignition, a flame it can't sense, or a pressure reading outside its limits — it shuts the burner down and refuses to fire until you tell it to try again. That instruction is the reset.

You typically know a lockout has happened because the boiler has gone cold, a warning light is showing, or the display is flashing a fault code (for example an L2, F-something, or a flame symbol with a line through it). Resetting is the correct first step for a one-off lockout. It is not a fix for a fault that keeps coming back.

Before you reset: three quick safety checks

A lockout is sometimes a symptom of a simple, homeowner-safe issue. Check these first — none of them involve removing the boiler casing:

• Power and fuse. Make sure the boiler has power and the fused spur or plug hasn't tripped. A boiler with a blank display has lost power, not locked out.
• Pressure. Look at the pressure gauge. Cold, it should sit at roughly 1 to 1.5 bar (rising to about 2 bar when hot). Below around 1 bar is low, and many boilers will lock out on low pressure. You can usually top this up yourself via the filling loop — see our guide on low boiler pressure.
• Thermostat, programmer and gas supply. Confirm the room thermostat is calling for heat, the timer is set to "on", and other gas appliances (such as a hob) are working — that tells you gas is reaching the property.

If you can smell gas at any point, do not touch the boiler, electrical switches or the reset button. Open windows, leave the property and call the National Gas Emergency line on 0800 111 999.

How to find the reset button

On almost every domestic boiler the reset is a front-panel control: you never need to open the casing. It is usually one of three things:

• A clearly marked "Reset" button.
• A button showing a flame symbol or a circular reset arrow.
• On boilers with a control dial, a reset position on the dial that you turn to and hold for a few seconds.

If you can't see it, the boiler's installation or user manual will show its exact location. Don't guess by pressing unlabelled buttons.

How to reset, step by step

1. Note the fault code or warning light first — it's useful if you do need to call an engineer.
2. Press and hold the reset button (or turn the dial to the reset position) for the time stated in your manual — commonly around 3 to 10 seconds.
3. Release. The boiler should run through its ignition sequence; you may hear the fan and a click as it fires.
4. Wait. Give it a few minutes to settle and confirm the heating or hot water comes back on and the fault has cleared.

That's it. If it fires up and stays running, you're done — a single lockout after a power cut, a brief pressure dip or a cold snap is rarely anything to worry about.

Brand notes: Worcester, Vaillant, Ideal and Baxi

The principle is the same across brands, but the control differs slightly:

• Worcester Bosch (Greenstar range): usually a dedicated reset button on the front panel; on models with a control knob, turn it to the reset position and hold.
• Vaillant (ecoTEC range): a clearly marked reset button, often near the display; hold it briefly to restart.
• Ideal (Logic, Vogue, etc.): a reset button on the front fascia, sometimes combined with the mode/select controls — check the labelling.
• Baxi (and the related Potterton/Main models): a front-panel reset button or a reset position on the control dial.

Whatever the badge, the action is always on the outside of the boiler. If a guide ever tells you to take the casing off to "reset" something, ignore it — that's engineer territory.

When to stop resetting and call a Gas Safe engineer

Resetting clears a fault; it doesn't repair one. Stop and book a Gas Safe registered engineer if any of the following apply:

• The boiler locks out repeatedly after you reset it.
• The same fault code keeps returning.
• Pressure keeps dropping even after you've topped it up (this can point to a leak).
• You notice banging, gurgling, a burning smell, or staining/soot around the boiler.
• The boiler is leaking water, or you can smell gas (call 0800 111 999 first).

Repeated lockouts are the boiler's safety system doing its job — telling you it isn't happy. Forcing it to keep restarting won't solve the underlying problem and could make it worse.

Where boiler cover fits in

Recurring lockouts often need a part replaced or a fault traced, and that's where a policy earns its keep: a good boiler cover plan covers the engineer's call-out and repair so a stubborn fault doesn't turn into a surprise bill. If you're weighing up whether it's worth it, our guides on the best boiler cover and cheaper options break down what's typically included. Landlords have extra obligations — see landlord boiler cover.

Frequently asked questions