How To Reset a Boiler: What You Need to Know

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Last updated: October 31, 2023
reset a boiler

To provide hot water and heating for your home, your boiler works 24 hours a day, 7 days a week. While they’re generally durable and low-maintenance systems, boilers are not indestructible and may occasionally shut down when a problem is detected. Great for the safety of the boiler, but unfortunately, not great for your home as a non-working boiler means no central heating. Thankfully, you can easily get your boiler working again by resetting it. Here’s exactly how and when you should do that.

When Does a Boiler Need Resetting?

Most modern boilers have a safety feature that allows them to shut down on their own the moment an issue has been detected. This is called a boiler lockout. You’ll know that it’s time to reset your boiler if it’s displaying an error code or if it’s flashing red or green lights. While a boiler lockout may be bad news for your central heating and hot water, it’s beneficial for the boiler itself as it prevents it from firing up when there’s a problem within the system.

While it’s always a good idea to hire a Gas Safe registered engineer to fix your boiler problems, you can definitely reset the boiler yourself. However, do make sure you reset it after the problem has been fixed.

What To Do Before Resetting A Boiler

Before you reset your boiler, you’ll have to diagnose and fix the problem. Unless you’re an engineer yourself, we do not advise you to experiment with this – it’s important to let a professional inspect the boiler and fix it as the problem could be serious. But, first thing first – read your boiler manual and visit the manufacturer’s website as this is where you can discover what the fault code that your boiler is displaying means.

If you’re having to constantly reset your boiler, it’s because you’re skipping one crucial step – fixing the problem before resetting the boiler.

How to Reset a Boiler

Once a Gas Safe engineer has diagnosed and fixed the issue that has caused your boiler to flash red light or display a fault code, you can reset the boiler. Here is a short and easy-to-follow guide that can help you do just that.

  1. Find the reset button: before you can reset your boiler, you have to find the reset button. On most modern boilers, this will be right on the boiler display, near the error code. If you have a new boiler and you can’t find the reset button, refer to your manual – it should tell you exactly where the reset button is.
  2. Hold the reset button: when you find the button, push it and hold it for about 5 to 10 seconds.
  3. Wait for the boiler to turn on: because all boilers are different, some will turn on immediately after being reset, while others will not. If your boiler doesn’t fire up immediately, simply wait for a few minutes. Many modern boilers go through a reset sequence, so wait for about 5 to 10 minutes.

Boiler Not Turning On After Resetting

If for some reason your boiler doesn’t fire up after being reset, all you have to do is repeat the second step – reset it again and wait a few minutes. If after two attempts your boiler still fails to turn on, you’ll have to check the gas supply to your property (if the heating engineer hasn’t already done this). If this seems fine, the most likely scenario is that the problem hasn’t been fixed. Remember, before you can reset your boiler, you need to have a heating engineer or boiler engineer diagnose the issue and solve it. If for whatever reason you haven’t called a professional but you’re confident you’ve fixed the problem yourself (you’ve checked the error code and its meaning in the boiler manual or manufacturer’s website and you’ve fixed the issue), here is what you can also try:

  • Make sure that there is power getting to the boiler. If you’ve experienced a power cut, it’s very possible that there is no power getting to the boiler. Check your fuse box and make sure everything’s alright. Also check the boiler – if there is power, the display screen will be lit.
  • Ensure you have a gas supply. If you haven’t already checked the gas supply to your home, now is the time to do it. You can do this by checking the cooker.
  • Check the pressure gauge for high or low pressure. If the fault code wasn’t about the boiler pressure, check the pressure gauge to see if the water pressure is too low or too high. Optimal pressure is typically between 1 and 2 bars, however, on some boilers the needle can read as high as 2.5 bar.

Why Has My Boiler Gone Into Lockout?

As mentioned, a boiler lockout occurs when a machine detects a certain problem or when it’s not operating within certain tolerances. This is a safety feature that all modern boilers have both for their protection and your own. While a boiler that’s not turning on is far from ideal (your heating system will stop working and you won’t have hot water), it’s good that the modern machines are designed this way as they’re able to recognize when it’s unsafe to continue operating.

A lockout can be caused by any of the following problems:

In essence, a lockout occurs when a machine shuts down due to a problem within a system. Resetting the boiler will usually fix the issue, however, this should only be done after a problem has been diagnosed and fixed either by an experienced plumber, or better yet, a Gas Safe engineer. Note, however, that if your boiler requires frequent resetting, it might be on its last legs. If it’s older than 10 years, you may want to consider getting a new boiler.

You may also like our post about the Best Digital Gas Manometer.


  1. How to reset a boiler – Viessmann
  2. How to Reset a Baxi Boiler – Baxi