Boiler Not Igniting – Six Reasons Why and How to Fix It

There are a number of different reasons why your boiler might not be igniting. In this guide, we will explain six of the most common causes of this problem and detail how you can resolve them. Some will require professional help, others are things you might be able to fix yourself. But all are problems that need to be dealt with properly if you don’t want them to get worse.

If you have had problems with your boiler not igniting and your central heating and hot water supply not working as a result, this is the guide for you.

In just five minutes, you can find out what the most common causes for a boiler not firing up are, and the best way to get the problem fixed.

It is important to note right at the start that boiler can be dangerous and if you are in any doubt at all about what you are doing, you should get help from a qualified gas heating engineer.

Some problems will be easy to fix and there may even be a DIY option if you are confident in what you are doing. But some will be more serious issues and might even require you to replace your boiler if it is old or the repair will be too expensive.

If you are in the market for a new gas boiler, we recommend you take a look at WARMZILLA. This online installation company offers hugely competitive prices on a wide range of high-quality boilers from all the best manufacturers.

You can get a fixed-price quote from WARMZILLA in just a few minutes by completing their online form. You don’t need to share any personal information and they can often install your new boiler as quickly as the following day. They also have some great discounts and special offers such as extended warranties too.

If you are in the market for a new boiler, make sure WARMZILLA is one of the quotes you get.


The Top 6 Reasons Why Boilers Fail To Ignite

In this section, we will outline the six most common reasons, in our experience, your boiler might not be able to ignite.

These reasons are not listed in order, but we have tried to keep the details as easy-to-understand as possible and outlined what we believe is the best fix, based on our years of experience in the heating industry.

#1 – Faulty Gas Valve

Your boilers gas valve is the part that controls the flow of gas into your boiler. If your boiler needs to generate more heat, this valve will open a little more and allow more fuel into the system. When it needs to cool down, the opposite happens.

Gas valves are vitally important, but they can also go wrong fairly easily too. There are a number of common problems that can occur with a gas valve including:

  • Blockages – an object or debris is blocking the valve from opening and closing properly.
  • SeizuresA problem with the mechanism is stopping the valve from working properly.
  • Damaged wired connectionsAn electrical issue is affecting the power supply to the valve.

Usually, these problems can be fixed relatively easily, although you will need a qualified gas engineer to do the work for you. A simple adjustment or service will usually do the job.

This is definitely not a job you can do yourself. If your boiler’s gas valve is adjusted incorrectly, it can be dangerous and wither cause your boiler to lockout or worse. Your boiler is likely to identify the issue as a problem with your gas supply and this can be a major issue to fix.

#2 – A Blocked Burner

Your boiler burns gas in much the same way that your car burns petrol and it produces carbon when it does so. This carbon can get clogged up inside the burner over time and eventually, this build-up can affect the performance of your boiler.

One of the most common symptoms of carbon build-up is your boiler refusing to ignite or igniting inconsistently.

This issue can usually be fixed with a simple clean. However, sometimes the carbon build-up can damage the burner and if it cannot be repaired easily, a replacement is a big job.

If you need a replacement burner, you are probably going to be better off buying a whole new boiler. If you buy from somewhere like WARMZILLA, which offers some of the best prices available anywhere in the UK, you could end up with a brand-new boiler for only slightly more than you would spend fixing your old one.

Speak with a qualified gas engineer before making any decisions. But if they recommend a new boiler, be sure to fill in WARMZILLA’s form to see how much money you can save.

#3 –Insufficient Gas Pressure Or No Gas Supply

One reason that your boiler might refuse to ignite is if there is no gas supply reaching it, or if the gas pressure has dropped too low.

Anything that involves the gas supply itself will require a qualified Gas Safe heating engineer. They will be able to test the gas supply and pressure at all the most important parts in your system including coming into your boiler, in the system itself, and when leaving your boiler.

Often they will be able to make adjustments to solve the problem, but sometimes it can be the symptom of a more serious issue.

If your boiler is struggling to ignite during a spell of cold weather, the problem could be with the Gas Meter. These Meters have a regulator fitted to them and in low temperatures, these can freeze.

The solution is usually to provide some lagging or insulation around the meter to protect it from cold weather and once this problem is identified, you can usually do this yourself.

#4 – Electrode & Ignition Lead Problems

If your boiler won’t ignite and you can hear a clicking or ticking noise, the problem could be with your electrode and ignition leads.

When these are the problem, your boiler is likely to still ignite, but on a more intermittent basis. If the problem is more severe, it might be a more serious issue.

You will need to call out a gas engineer to test the function of the electrode and ignition lead using a multimeter. If they are the cause of the problem, he will usually be able to install a replacement. This fix is far easier than trying to repair them.

#5 – The Fan Isn’t Turning

Your boiler contains a fan which is intended to create a draught inside the device. This draught pushes the harmful gases created by your boiler down the flue and safely outside your property.

If there is a problem with your fan and it is not turning, or a problem elsewhere in the system that means your boiler thinks the fan isn’t turning, this will trigger a safety feature in your boilers printed circuit board that will stop your boiler igniting.

This is designed to ensure that your boiler cannot create more dangerous gases if it is unable to get rid of them safely.

You can usually tell if there is a problem with your boilers fan because you can hear it. If your boiler isn’t igniting, listen to the boiler closely and see if you can hear the fan turning. If you can’t this could be the problem.

You will need a qualified gas engineer to take a look and see what the problem is. Replacing a fan is a big and expensive job, so you are better to try and fix the problem if you can. Fitting a new motor is a common fix which often works.

#6 – Extinguished pilot light

Most people know that their boiler has a pilot light and if this has gone out, the boiler won’t work. If the pilot light has been extinguished, the boiler will not ignite until it has been relit.

The jet of gas that feeds the pilot light is extremely small and it is very easy for a small bit of dust or debris to block this jet and put the pilot light out.

Sometimes this can be removed, cleaned, and replaced but you will need an engineer to do this job for you. If this doesn’t solve the problem, you will need to replace it. Don’t worry, they are relatively cheap to replace.

Other Causes Of Boiler Ignition Failure?

While these are the six most common causes of your boiler failing to ignite, the truth is that there are hundreds of other possible reasons.

Usually, these will be safeguards put in place to protect your boiler or yourself if there are problems elsewhere in the system. This is called a lockout.

If your boiler locks out, you will usually need to call out a gas engineer to get the problem resolved safely. When it comes to gas boilers, it really isn’t worth taking the risk.


A gas boiler failing to ignite is one of the most common problems they can have. There are a lot of possible causes for this and we have detailed the most common ones in this guide.

A few have possible DIY fixes, but usually, it is best to get a qualified gas engineer to take a look for you.

A lot of issues can be fixed with a clean or a readjustment, but sometimes you might need a new part or component to get things going again. This can be expensive and, on occasion, you might be better off getting a whole new boiler than shelling out to fix your old one.

If you do, we recommend taking a look at WARMZILLA, the online boiler installation service that offers some of the best prices and deals available in the UK.

Have you had a problem with your gas boiler failing to ignite? How did you deal with it? Did you need to buy a new component or did you need to get a whole new boiler? Do you have any tips for our readers that we haven’t covered in this guide?

It is always helpful to hear about the real-life experiences of other readers, so please do share yours with us using the comment box below.

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