Worcester Boiler Problems: Common Fault Codes + How to Fix Them

If you have a problem with your Worcester Bosch boiler, you are probably worrying about a big bill to get it repaired. But that doesn’t have to be the case. In this guide, we will explain eight of the most common faults that can occur on a Worcester Bosch boiler and show you how to fix them. Some of these fixes are really simple and things that you can do by yourself. That means this article could save you a bundle on your boiler repair costs.

Worcester Bosch boilers are some of the most dependable models on the market. But even the best boilers go wrong from time to time and when yours does, the first thought you have is almost certainly going to be, “Oh no, how much is this going to cost?”

Worcester Boiler Faults

But don’t worry. In this short guide, we will explain what is causing the most common faults that can occur on Worcester Bosch boilers. We will tell you what the fault means and what you can do about it.

The information included in this article has been advised by our panel of heating engineers and other sector experts. Not every fault can be fixed easily and cheaply, but many can, so it is just possible that this article could save you a packet.

What happens when there is a fault code on your Worcester Bosch boiler?

When you get a fault on your Worcester Bosch boiler, your control panel will show a fault code. This code starts with “EA” and is intended to tell you what the problem is.

To find out what this code means, you should consult your boilers handbook or take a look on the Worcester Bosch website.

This should be able to give you an idea of what the problem is and it will sometimes give you advice on how to fix the problem too.

However, it will often advise you to seek professional help. This is sometimes necessary but not always. Some problems can be fixed quite easily.

RELATED READING: What size boiler do I need?

In this guide, we will summarise the eight most common faults our panel of experts has seen on Worcester Bosch boilers and explain how to fix them.

8 Most Common Worcester Boiler Problems

#1 – No Hot Water

If your Worcester Bosch boiler isn’t producing hot water, there are a few possible issues that could be causing the problem.

It is possible the issue is caused by a faulty diverter valve. If your heating is working but the hot water isn’t, this is the most likely issue.

Other possible problems include a stuck Y/S-plan valve, a faulty PCB unit, or an issue with the heating pump, or even a problem with the power supply.

The Fix

If you have a problem with your diverter valve, you are likely to have either cold or luke-warm hot water, lots of hot water but no heating, or you might find your hot water only works when your heating is on.

Replacing the valve is likely to cost anything between £250 and £350. This includes the replacement part and the installation costs. You will need a qualified engineer for this job. There are no short cuts.

If your boiler is a fairly old one and out of warranty, you might want to consider replacing the whole boiler rather than paying out a big sum for a new part and risking something else going wrong a few months down the line.

If you want to get a new Worcester Bosch boiler, the best place to look is WARMZILLA. They offer a great range of boilers at the lowest possible prices and can arrange installation as quickly as the following day.

Just head over to the WARMZILLA website and fill in their online form for a fixed-price quote. It will cost more than a new diverter valve but could end up saving you money in the long run.

#2 – Boiler Is Leaking

A leak on a Worcester Bosch boiler is usually caused by a damaged or blown pump seal. This can be a big problem because it can lead to low pressure and result in a boiler lockout.

Pump seals do degrade over time. They can also develop problems if you have made a change to your boiler, such as increasing the flow rate, which puts them under increased pressure.

This is a fault that your boiler should recognise so if your leak is being caused by a blown pump seal, the boiler should display a fault code. This is likely to be either A 281 or EA 338 depending on the model of Worcester Bosch boiler you have.

The Fix

A leaking boiler is a problem that you can sometimes fix by yourself. If you can identify the source of the leak, you can use a leak sealant to fix the problem.

But if the problem is being caused by a damaged pump seal, you will need professional help. A heating engineer is able to replace the seal alone but you might also want to look into the economics of replacing the whole pump.

It is actually a lot harder to replace a seal than a whole pump so this will keep labour costs down. And the price of a new seal is not that much less than a whole new pump. Take the advice of your engineer, but it is well worth considering.

Do be sure to remember that once you’ve fixed the leak, you reset your boiler to the correct pressure. This is 1.3 bar.

#3 – Blocked Condensate Pipe

All Worcester Bosch condensing boilers have a condensate pipe which will ensure that any dangerous gases generated by the boiler are vented outside.

Unfortunately, it’s a common problem with Worcester Bosch and some other brands for this condensation pipe to become blocked.

If this is the problem with your Worcester Bosch boiler, you will see the code EA 229 displayed on your boiler’s panel.

The Fix

The first thing to do is to check your boiler’s condensation pipe for any obstructions you can remove manually.

If it is cold weather, it is quite likely that the pipe could have frozen. If that is the case, you can easily thaw out the pipe with some warm water. If you then reset your boiler, you should find the problem has been resolved and the error code disappears.

If your condensing pipe has frozen, you should take steps to stop this from happening again. This is also a simple process. You just need to lag the pipe to keep it warm and the fault shouldn’t reoccur.

#4 – Pressure loss

When your Worcester Bosch boiler starts to lose pressure, it is likely that your boiler has a leak.

This could be on the boiler itself or anywhere in your heating system. It could also be something that is very hard to spot such as a pin-hole in a radiator or a loose connection in your pipework or on a radiator valve.

The Fix

If your Worcester Bosch boiler drops below a certain pressure, it will lock you out. It is possible to solve this issue temporarily by using the external filling loop to re-pressurise it.

But to solve the problem and clear any fault codes, the leak needs to be found and fixed.

If you can spot where the leak is coming from, you may be able to fix the problem yourself using a leak sealant. If not, you will need to call out a heating engineer to fix the problem for you.

#5 – No Power

If your Worcester Bosch boiler is not getting any power, the cause could be a number of things.

If there has been a power surge you could have blown a fuse or your RCD could have tripped. You could even have blown a fuse in your spur.

If you get power on an electric meter, you might have run out of credit. There could also be an issue with the power light, or you could have an issue with your Printed Circuit Board (PCB).

The Fix

If the problem is caused by a fuse, this can be easily fixed by either flipping the switch on your RCD or replacing the blown fuse.

If you need to add credit to your electric meter, this can be done in various ways depending on your provider, and if there is a problem with your meter that is causing the fault, this can be fixed easily by contacting your electricity provider too,

If the problem is as a result of an issue with your PCB, this is a more serious issue. PCB’s do go wrong and the cost of replacing them is not cheap. You can expect to pay something in the region of £500 for this fix.

If this is the problem and your boiler is an older model and out of warranty, most engineers will probably recommend replacing the boiler. If you look at the prices for a brand new, energy-efficient Worcester Bosch boiler on WARMZILLA, you can see why.

For just three times the price of patching up your old boiler, you can get a brand-new one and many come with extended warranties and great prices too.

Just fill in their online form to get a no-obligation fixed price quote.

#6 – Banging noises from your boiler

Banging noises from your boiler are an extremely common issue. They are usually caused by two things.

Either you have a heat exchanger that is kittling or you have an airlock in your central heating, in the pump.

Other possible but less common causes include a buildup of sludge or limescale inside your boiler, low water pressure or a low flow rate, or a blocked or broken heat exchanger.

If your boiler is making a humming noise, this is most likely to be caused by a seized part in your central heating pump.

The Fix

If the problem is caused by an airlock, there is good news. Most Worcester Bosch boilers come with a bleed screw that lets you bleed the pump in much the same way as you do your radiators.

Limescale and sludge build-ups usually need a system flush and this will have to be done by a heating engineer. If you have a low flow rate, this can usually be adjusted in your boilers settings.

The most serious problem is if you heat exchanger has an issue. This is likely to mean it needs replacing and this is not a cheap part. Once again, if your boiler is an older model and out of warranty, most engineers would recommend you replace the whole thing and WARMZILLA is the cheapest place to look to do this.

#7 – Boiler Keeps Locking Out

All Worcester Bosch boilers are fitted with safeguards. These are designed to lockout whenever there is a problem such as overheating, a large loss of pressure, or if they are working too hard.

The reason for these lockouts is simple. It is an e-stop for if the boiler thinks it could be dangerous. And it is also a safety measure to protect your boilers vital components.

If your Worcester Bosch boiler locks out for one of these reasons, the most likely fault code you will see is EA 227.

The Fix

If your Worcester Bosch boiler is repeatedly going into lockout, you should check the error code carefully to see what it is reporting as the problem.

It is usually possible to reset your boiler and get it working again. But this is only a short-term fix and if the problem persists, the lockout will return too.

Our best advice is to check all of the errors outlined in this guide. But if the problem is being caused by something else, you are probably best advised to seek professional advice from a heating engineer.

#8 – Boiler Overheating

One of the most common boiler faults is an overheating boiler. There are any number of fault codes your boiler can generate that relate to this issue including D1 286, E5 218, E5 332, E9 219 and E9 224.

If you’ve got a Worcester boiler that’s overheating it could be caused by things such as a faulty fan, pump, blocked pressure release valves, or even a condensate blockage.

It can also be caused by limescale buildup, sludge deposits in the system, or an overheating central heating pump.

The Fix

If the problem is caused by a buildup in the system, a flush will be needed to clear things out.

If it is an issue with your pressure release valves, central heating pump, or the fan, the best bet is to get a qualified heating engineer to assess and fix the problem.


There are lots of different reasons why your Worcester Bosch boiler could develop a fault.

In this guide, we have outlined the eight most common and shared the top tips of our industry experts on how to fix the issue. As you will have seen, some repairs can be done yourself, but others need professional help.

If your repairs are going to set you back several hundred pounds, you might also want to consider replacing an older boiler that is out of warranty with a new, energy-efficient one.

The best prices on a new Worcester Bosch boiler can be found at WARMZILLA where you will also have a range of extended warranty deals and some great finance packages available too.

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