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Boiler Lockout? Here’s How to Reset a Boiler

Need to know how to reset your boiler? When a boiler detects a problem, it will lock out — it’s a safety feature meant to shut the appliance off in a dangerous situation. Once you’ve established and fixed the underlying issue, you’ll have to reset your boiler to get it to ignite.

This quick guide will show you how to reset a boiler once you’ve determined why it locked out in the first place.

How to reset a boiler
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What to Do Before Resetting a Boiler

A boiler lockout could happen due to 1 of 2 things:

  • The boiler is aware of a fault that won’t allow it to work correctly (such as low pressure)
  • The boiler recognises that it’s unsafe to continue operating (for example, in the event of high water pressure, or a bad gas supply)

So before you attempt resetting your boiler, have a flick through our guide to why boilers lockout to determine the problem.

How to Reset a Boiler

Below are some generic instruction on how to reset a boiler. After you’ve read these, you should be able to reset most boiler models out there. However, we also included brand-specific boiler reset instruction at the end of this article.

#1 – Diagnose and Fix the Fault

After experiencing a lockout, a boiler will display a fault code.

You’ll need to diagnose the error code and fix the problem before continuing.

If you’re having to constantly reset your boiler, it’s because you are not clearing the fault before resetting it. So, the boiler locks out to protect its internal parts, and your safety.

When you’re unsure what the fault code means, you have two options:

  • Consult the owner’s boiler manual
  • Contact a Gas Safe boiler engineer to diagnose and fix the problem (advisable)

#2 – Find The Reset Button

Most modern boilers will have a reset button that’s located on the boiler’s display, near where the fault code is being shown.

As an example, this button on a Vaillant EcoTec will be flame with a line through it. This is the reset and ignition button.

If you can’t locate your boiler’s reset button, refer to the owner’s manual — most have a dedicated How to Reset Boiler section with specific instructions for the given model.

#3 – Press And Hold The Reset Button

Once you’ve found it, press and hold the button for 3-10 seconds. The exact time you’re meant to hold the button varies between boilers, so you’ll have to double-check the manual. That said, the majority of models will reset after the button is held for 3-5 seconds.

#4 – Wait For The Boiler To Fire Up

Not all gas boilers will fire straight up after being reset; most modern models will need to go through a reset sequence.

And this could take 5-10 minutes.

If you’re confident you’ve found and fixed the fault, pressed the reset button, and the boiler isn’t resetting, it’s time to call in a Gas Safe engineer.

How to Reset Your Boiler — Brand-specific Instructions

Now that we’ve walked you through the general instructions, let’s go over the reset procedures for some popular boiler brands.

How to Reset a Worcester Boiler

Most newer Worcester Bosch models, like the Greenstar SI and CDi, will have a boiler reset button right next to the display. All you have to do is press the reset button (or press and hold it for several seconds, like with the CDi Classic). If the fault indicator ceases flashing, you’ve reset your boiler successfully — at least for the time being.

Other models, like the Greenstar Ri, have a “reset” position on their temperature control knob. In this case, simply turn the knob to “reset” and hold it there for 5 seconds. Then, return it to the desired temperature setting. Again, if your boiler reset is successful, the flash indicator will stop flashing.

Vaillant Boiler Reset Instructions

Once you’ve fixed the underlying cause, Vaillant boiler reset becomes a breeze. On your Vaillant boiler, the reset button should be on the display; press it and hold this button for 3 seconds before letting go. If the fault code has disappeared and your boiler’s fired up, go ahead and check whether your radiators are heating up and if you’ve got hot water in your taps.

If your Vaillant boiler doesn’t fire up after the reset, you may have another root cause to investigate with the help of a Gas Safe heating engineer.

Procedure to Reset an Ideal Boiler

The steps to reset an Ideal boiler will vary depending on the age of your boiler model.

If you’ve got a newer Ideal boiler (like the Ideal Logic+) you have 2 options:

  1. Press the boiler reset button under the display screen
  2. Find the reset button in the display screen menu

In either scenario, see if hitting the reset button will clear the fault codes and get your boiler to fire up.

Now, if you’re using an older Ideal model, you may have “reset” as a dial position. If this is the case, just turn the dial to “reset” and hold it there for 3 seconds. Once again, make sure your boiler ignites and the fault code disappears.

How to Reset a Glow Worm Boiler

On newer Glow Worm models, the reset button should be right beneath the display — press it, and see if this clears the fault code or indicator.

If you have an older Glow Worm, the instructions are much the same. Note, however, that you may have to spend some time looking for the reset button, which might be hidden under a cover with other boiler controls.

Boiler Still Won’t Work?

Does your boiler refuse to fire up even after troubleshooting and resets? Or are you finding that your repair bills are piling up? If so, it may be time to consider buying a replacement boiler.

You can get started by getting a quick boiler replacement quote from Heatable here. The online boiler installation company have some of the most competitive prices for a range of boiler models, along with a price-match guarantee and flexible finance options. All you need to do is fill out Heatable’s anonymous questionnaire about your central heating setup and you’ll get your fixed-price quote on the screen.

Heatable boiler installations

What’s Next?

We’re always happy to offer help.

If you can’t reset your boiler, or it keeps locking out after a reset, leave us a comment below and we will get back to you as soon as possible.


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  1. Matthew Ronalds says:

    I have been unable to reset the boiler after lockout. So far the control box and pump have been replaced. The fuel level is low.so having checked the parts and fitted them it restarted for a while but then lock down again and will not restart

    1. heatingforce says:

      Hey Matthew,

      Do you mean the pressure gauge on the boiler is low? If so, sort that first.


  2. Alan says:

    I have a worcs combi boiler greenstar tried to reset but keeps failing saying code 227 ionisation fault

    1. heatingforce says:

      Hi Alan,

      Where is your gas meter located? Regulators on meters freeze easily, so if it’s outside and exposed, there’s a good chance it’s that.

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