Five Common Baxi Boiler Problems: Solutions and Troubleshooting

Baxi boilers are among the most popular in the UK thanks to their competitive prices and reputation for reliability. But even Baxi boilers can go wrong from time to time. In this guide, we will explain the five most common faults that can occur with a Baxi boiler and explain how you can fix them.

Baxi boilers offer a great combination of reliable engineering and low prices. But when they go wrong, it can be hugely frustrating.

While there are a lot of different things that can cause a boiler to go wrong, some faults are far more common than others.

In this guide, we will outline the five faults which we have seen occurring most frequently in Baxi boilers. We will explain what is causing the issue and how you can fix it.

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Most Common Baxi Boiler Problems

Some fixes are DIY things you can do yourself and save money on calling out an engineer. But others will require the help of a qualified professional.

And it also goes without saying that if you are in any doubt, you should always call out a Gas Safe qualified engineer and not mess about with your boiler and your gas supply yourself.


#1: A Visible Leak from Your Boiler

All boilers can develop leaks from time to time, but this is a problem we have seen particularly frequently in Baxi boilers. The Solo range, 105HE and 133HE Plus appear to be particularly prone to it.

The cause of such a leak is likely to be either an issue with the pump or a problem with the housing for the diverter valve. Both of these components contain seals and over time, it is quite common for these seals to degrade or come loose.

This is particularly common if they come under excessive pressure, so if your boiler is set to a pressure that is too high or a blockage elsewhere in the system is causing a pressure build-up, this can also bring on a problem like this.

Because Baxi boilers tend to be in a lower price bracket, they do contain some parts that are made of plastic too. Boiler vibrations can cause these plastic components to crack over time and this can result in leaks, especially in the housing around the diverter valve.

How to Fix it:

You will need to get a qualified engineer out to identify the cause of your leak and to execute the fix.

If it is one of the two common problems we have identified above, your engineer will be able to get hold of a spares kit produced by Baxi to fix pumps and various internal housings.

However, the labour costs involved in installing these spares can often end up costing more than just buying a whole new component. Be sure to check this with your engineer before proceeding.

You should also ensure that your engineer checks all the other components within your boiler too, especially the electrical parts. Water leaks can cause damage to other parts too and if this is the case, it may well make better economic sense to replace the whole boiler rather than fix all of the damaged parts.

#2: Can Only Get Hot Water Or Heating, Not Both

It is quite common in Baxi boilers, and boilers of most other manufacturers, for either your central heating or hot water to be working, but not both.

If your heating is on, but your shower can only get up to tepid temperatures, or your shower works fine but your radiators are only luke-warm, this is usually an indicator of one thing; a diverter valve issue.

The diverter valve is the component within your boiler that directs the hot water it produces to where it is needed. If there is a problem with is, it is quite likely that hot water is able to get to one system but not the other.

How to Fix it:

Fixing the diverter valve means taking apart the boiler, so you will need a qualified engineer to do this job for you. They will be able to take a look at the diverter valve and see whether it is blocked or whether it has a more serious problem.

If it is just blocked, a simple clean and service should resolve the problem. If the problem is more serious, they are likely to recommend replacing the whole part.

A new diverter valve is likely to cost you between £250 and £300 and possibly even more, depending on labour costs.

If your boiler is very old and out of warranty, this is quite a significant sum to invest, so you might want to consider spending a little more and getting a whole new energy-efficient gas boiler installed instead.

#3: Boiler Noise

It is quite common for people to report noise coming from their Baxi boilers. This is usually a banging noise and doesn’t tend to be constant, but rather it occurs when the boiler is cycling on and off. Sometimes it also happens when the boiler is started up for the first time too.

There are a number of different things that can cause this issue and, once again, you need to get inside the boiler to work out what the problem is. This means that, unfortunately, you will need the help of a qualified engineer once more.

How to Fix it:

Your engineer is likely to want to run a series of tests to work out what is causing the noise. In our experience, the most likely culprit is a broken burner. This is a critical component within the boiler, but they can go wrong surprisingly quickly. We have seen broken burners in boilers a young as four years old but it is more common in boilers aged six or older.

If your Baxi boiler does have a broken burner, it is likely to be showing a 128 fault code on the display panel.

If the fault is caused by something more severe than a blockage, then you are likely to need to replace the burner entirely. This is another fairly major repair and could set you back anything from £300 – £450 all in.

If this is the case and you have an older boiler, we would once again suggest you consider a replacement boiler rather than spending such a large sum on an old boiler which could have something else expensive go wrong just a few weeks down the line.

Discuss your options with your engineer and decide what makes the best financial sense for you.

#4: Boiler Keeps Locking Out

Boiler lockouts are almost always a failsafe mechanism, but they can be far more common on some boilers than others. We have found that some Baxi boiler models, in particular the Baxi Solo 1PF and 2PF, are especially prone to regular lockouts.

The issue usually come back to a problem with overheating. This is a major problem which is why the boiler will lockout to protect other components from overheating and becoming damaged.

Unfortunately, identifying the root cause of an overheating boiler is tricky. It can generate a number of different fault codes including 110 (overheating), 160 (a faulty fan) and 166 (an air pressure switch fault).

How to Fix it:

A common cause of boiler overheating in Baxi boilers is low pressure. If your Baxi boiler is set to lower than 1.5 bar, the chances are that it will not operate correctly.

The good news is that this is a problem you can fix yourself. You can top up the pressure in your boiler using the filling loop which you will find just underneath the casing. Check your boiler manual to find the precise location if you are unsure.

Having topped up the boiler to the recommended pressure (again, check your manual for this), you will then need to reset your boiler. To do this, you will need to press the orange button (on a Baxi Solo 1FP) or the red button (on a Baxi Solo 2FP).

If the loss in pressure reoccurs, this means there is another problem that is causing your boiler to lose pressure. The most common cause of pressure loss in a boiler is a leak.

This can be within the boiler but can also be anywhere in your central heating system too. You can try to locate the leak yourself by checking things like radiators, towel rails, exposed pipes, valves, and pipework around your boiler.

If you can find the leak, there are DIY products you can use to fix it yourself, but to be safe, you will probably want to get a trained engineer out to fix it.

#5: Ignition Problems

Another common cause of boiler lockouts is a problem with the ignition. If the boiler is unable to light, it will lockout to prevent any gas escapes or other potential safety issues.

This issue is seen fairly frequently in some Baxi boilers, especially the Baxi 100e and 105e.

How to Fix it:

This is another problem that will require an engineer to take a look. They will run through a series of tests to determine the cause of the problem and see if there is a problem with the ignition.

Things they are likely to check include your gas supply, the leads that connect to the ignition, your boiler’s combustion chamber and seals, and the gas valve.

If there is, it is likely that they will simply replace the ignition. This is a fairly straightforward job, which shouldn’t cost you too much money.

However, if the problem is caused by something else, the fix could be bigger and more expensive.

Where to buy a new boiler?

If your Baxi boiler does require an expensive fix and your boiler is already pretty old, you may well be better off buying a whole new boiler.

New boilers are more energy-efficient, so will save you money on your utility bills as well as bring a healthy warranty, which means you should have any other repair costs for several years.

If you are going to buy a new boiler, you should always get several quotes and we would strongly recommend you take a look at Heatable for one of them.

Heatable is an online boiler installation service that offers some of the best available prices on the market on a wide range of boilers from Baxi and all the top boiler manufacturers. It has some great special deals including extended warranties available too.

Be sure to get multiple quotes before buying a new boiler, but we would strongly recommend one of them is from Heatable.


Like all boilers, Baxi ones can develop faults from time to time. In this guide, we have outlined the five most common faults we have seen on Baxi boilers. We have indicated the likely causes and explained the best way to fix them.

Some fixes are relatively simple and things that you can do yourself. Others are more complex and will need the help of a qualified engineer.

In some instances, you may need to get a whole new component. This can be expensive and if that is the case you might want to consider investing in a whole new boiler. If you do, we have recommended that you get a quote from Heatable, an online installation company that offers some of the most competitive prices around.

Have you a problem with your Baxi boiler?

Did the fixes outlined in this guide help? Do you have any other questions for us or tips for our readers based on your own experiences? If so, please do share them with us using the comment box below

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