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8 Common Worcester Boiler Faults [And What To Do Next]

Welcome to our 10-minute guide to Worcester Greenstar boiler faults.

Got boiler problems with your Worcester?

No worries. This article will explain what they mean, and what you need to do next.

We’ve also referenced detailed articles on each of the Worcester boiler problems listed, so you can get the fault fixed.

Fed up with your boiler? You can get multiple boiler repair quotes from local heating engineers from RatedPeople here.

Or, if you’re ready to ditch it for a new one, you can get a fixed price online from BOXT (part owned by Bosch), from £1,695.

What Happens When You Get A Worcester Boiler Fault?

Before we start, it’s worth noting this. When a problem occurs with your Worcester boiler, your  control panel should display a fault code. Worcester Boiler Problems

In the case of Worcester boilers, their fault codes start with EA.

The Worcester EA fault code will give an indication of the problem.

You’ll be able to find the cause of the fault by referencing the fault code, in your owner’s manual.

8 Common Worcester Boiler Faults

#1 – Blocked Condensate Pipe

Condensing boilers like Worcester Bosch, have a condensate pipe. This vents harmful gases from your property.

Unfortunately, it’s a common problem with Worcester’s that the condensate pipe gets blocked. This will cause a EA229 fault code to be displayed on your boiler.

The Fix

Check the condensate pipe for obstructions.

If it’s a chilly morning, or winter, there’s a good chance that the pipe’s gases have frozen and caused a boiler lockout.

Simply thawing out the pipe with warm water and resetting your boiler will clear the E229 fault code.

Next, you want to stop this from happening again.

You’ll need to insulate the pipe using lagging. Normal lagging will do, but ArmorFlex lagging offers much better protection.

#2 – No Hot Water

Is your Worcester boiler problem relating to no hot water? There’s a few scenarios that can lead to lack of hot water.

These include a faulty diverter valve (typical, if the heating works, but hot water doesn’t).

But, it could also be due to lack of power, a stuck Y/S-plan valve, faulty PCB unit, or even a problem with the heating pump.

The Fix

You can diagnose a faulty diverter valve here.

If that doesn’t sound like the issue, head over to our article specific to Worcester boiler faults causing no hot water.

Alternatively, speak to a boiler repair company, we recommend using Rated People to find a local boiler repair specialist.

#3 – Boiler Is Leaking

If your Worcester boiler is leaking, this can cause low pressure, and the boiler to lockout.

A leaking boiler will usually be due to blown pump seals.

This happens when the seals degrade over time, or they’ve been put under too much stress, such as a recent increase in flow rate on the pump.

The boiler recognises this and displays a fault code. In this case, it’s likely to be the A281 or EA338.

The Fix

Before you call a Worcester boiler engineer and spending £100s, it’s worth checking this can’t be fixed on a DIY basis.

Not all leaks are serious, so an engineer isn’t always needed.

We’ve created a guide to skip through if your boiler is leaking.

This will help diagnose the fault, and get it fixed.

(Note: Once you’ve fixed the leak, make sure you boiler is set to the correct pressure, which is 1.3 bar)

Most small leaks can be stopped using Fernox’s F4 leak sealant for heating systems.

Remember, a leak is directly connected to boiler’s losing pressure…

#4 – Boiler Losing Pressure

If your Worcester boiler problem relates to your unit losing pressure; you have a leak.

Sure, it might not be visible, but it’s there somewhere. And, this is not necessary a leak on the boiler. Any leak throughout your central heating will cause a boiler to lose pressure.

This could be a pin-hole in a radiator, a loose connection on a rad valve, or even a weak soldering joint on copper pipe.

The Fix

When a Worcester boiler gets below a certain pressure, it will lock out. To fix this, you’ll need to re-pressurise it using the external filling loop.

But, that’s only a temporary fix. To solve the problem with your Worcester, and clear any fault codes, the leak needs to be found and fixed. You can get a repair company to fix your leak here.

Checkout our guide to boilers losing pressure here.

#5 – No Power To The Boiler

No power to your Worcester boiler? No problem.

Lack of power can be caused by a faulty PCB, an RCD unit that’s tripped or a spur socket that’s tripped.

The Fix

We’ve created a guide for homeowners with no power to their boiler here, to help diagnose and fix the problem.

#6 – Boiler Is Making Banging Noises

If your Worcester boiler fault relates to loud banging noises, there’s a fix.

The two most common causes of the problem are:

  • An airlock in the central heating pump.
  • A heat exchanger that is kettling.

The Fix

Jump over to our article that covers noisy boilers here.

As you’ll see, an airlock in a pump on a Worcester Greenstar boiler isn’t exactly difficult to remove.

However, if the problem with your Worcester relates to a heat exchanger, it might need replacing.

Unfortunately, heat exchangers are not exactly known for being cheap.

#7 – Boiler Keeps Locking Out

Does your Worcester boiler keep locking out?

All Worcester boilers are fitted with safe-guards. When they overheat, lose too much pressure, or are operating above their working pressure; they lockout.

Why? It stops any internal components getting fried, but it also stops the boiler working if it’s dangerous.

In this case, it’s most likely the fault code is EA 227.

The Fix

If your Worcester boiler fault is a constant (or intermittent) lockout, we’ve created a guide just for you.

Jump over to our ultimate guide to boiler lockouts here.

#8 – Worcester Boiler Overheating

Have you checked your Worcester boiler fault code, and found it relates to a boiler overheating?

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

Some common overheat fault codes include D1 286, E5 218, E5 332, E9 219 and E9 224.

The Fix

If your EA fault code relates to a overheat, checkout our quick guide on boilers overheating here.

What’s Next?

Still having problems with your Worcester Greenstar boiler?

Get a repair quote from local boiler repair engineers at RatedPeople here. Or a fixed online replacement price from BOXT here.

And, if you want some help, we’re happy to offer that for free.

Just drop a comment below and we’ll get back to you as soon as we can.

Leave a Comment:

S D Olphert says 17th February 2018

My Worcester Bosh Combi gas boiler is only 3 months old. I have found that on several occasions when I have turned the boiler completely off using the Honeywell wireless control it continues to run for approx. 10 minutes and steam is still being emitted from the exhaust flu leading me to be of the opinion that the boiler is still fired up. Is this normal.

    heatingforce says 2nd March 2018

    That sounds too long. It will run for a little while. Hot water needs to be pump out of boiler, and flue gases expelled via the flue with help from the fan. But, that’s usually a minute or two at most.

    Has it always been like that? If it has I’d get the engineer to come back and make sure the controls are synced correctly.

Paula hallett says 1st March 2018

The condensation pipes are frozen and the boiler is flashing pressure is nil I have tried resetting it should I turn boiler off until the thaw or take pipes off of wall outside and thaw them out
I’m insured with British Gas but they aren’t answering their phones even I just need to k ow should I switch
Boiler off for safety
The boiler is a Greenstar 24i/ junior registers 2012

Dino armenis says 2nd March 2018

My boiler Isent working …says it has a ignition fault ..what do I do ?

    heatingforce says 2nd March 2018

    Does it ignite and cut out? Not ignite at all?

    What’s the fault code that’s being displayed on the control panel?

Peter Hilliard says 2nd March 2018

the pressure on display of worcester bosh grecnstar cdi is reading.——2.4 bar is that ok.?? Thank You in anticipation.


    heatingforce says 2nd March 2018

    Is that when hot or cold? It sounds too high either way.

    A quick guide on boiler pressure here Peter:

Armida says 2nd March 2018

Hi I’m asking for my partner mum she got gas but no heating is coming on what shall they do in the meantime till the company comes out

    heatingforce says 2nd March 2018

    Without more details…a lot of boiler breakdowns in freezing cold weather are a frozen condensate pipe that needs to be thawed out. It’s a small (usually white and 21.5mm) pipe on the external of your property.

Elizabeth Burns ve says 2nd March 2018

My pipe is external and freezes as soon as thee weather gets bad the plpe goes up too high so can not reach the full pipe to pour hot water I am 70yrs old and only able to reach the bottom of plpe If I had known this I would not have changed my boiler but it was a goverment scheme to upgrade my boiler. I have been without heating for the last 3 days and you can appreciate the scottish weather does not help

    heatingforce says 2nd March 2018

    If it happens every year you can have someone:
    Fit a bigger pipe
    Re-route is so it drops as steeply as possible, so waste gases don’t linger for longer than they need to
    Get them to lag the pipe

    Hope that helps?

Margaret Gregson says 5th March 2018

Hi I have a Worcester Bosch and since Friday its not been working , on switching the boiler on the window is displaying preheating and the numbers are in creasing but the pressure is not moving off zero, I have tried filling it by the flexi pipe and turning the valves but its not moving the needle the window then goes on to display 201 DHW SYSTEM HEATING then 305 DOMESTIC HOT WATER SYSTEM and then 203 STAND BY MODE. PLEASE CAN YOU HEL ME.

    heatingforce says 5th March 2018

    Can you get someone to check if the water is coming out the overflow pipe outside?

      Margaret Gregson says 5th March 2018

      It did when I first started to fill it but now if I attempt to fill it it ju st keeps filling but the gaga won’t move

Margaret Gregson says 5th March 2018

Every Time I turn the water pressure on it comes out of the over flow yes

Margaret Gregson says 6th March 2018

??? I have lured boiling water over the out side pipe just in case of freezing.

Margaret Gregson says 6th March 2018

It did when I first started to fill it but now if I attempt to fill it it just keeps filling but the gage won’t move still. I have also bled my radiators .

Adrian says 6th March 2018

Hi guys, I have a problem with a Worcestor 27 cdi boiler. I have hot water but no heating . I tried a Lot of things check thermostat power going to it l link Ls and Lr nothing happens can someone help.

    heatingforce says 13th March 2018

    Typically sounds like a diverter valve but don’t replace it unless an engineer is sure!

Matt Lane says 16th March 2018

After 6 years of having a WB Greenstar Combi Boiler installed I have in the last month constantly found the pressure has dropped from 1.5 To 1 Bar and when the Heating is on the pressure is rising to over 3 Bar, but no Fault Codes are being displayed. After doing some research I found that a common fault is the Expansion Vessel and Pressure Relief Valve on this Boiler.

    heatingforce says 26th March 2018

    Hey Matt. Yup. That’s common.
    There’s more details here if anyone else is have pressure fault codes showing up:

John Cridge says 23rd March 2018

I have a Worcester Greenstar 40cdi. Just recently the boiler independently starts and continues to heat and warm the radiators after the room stat has sent the ‘off’ signal. The boiler responds to roomstat temp increase and decrease but after initially responding to an ‘off’ signal the boiler will start up and continue circulating making the pipes and rads very hot. Although the room stat is set at 8 the temp will continue to rise until I reduce the water heat control knob on the boiler.
No fault signal shows, I have tried switch off/on and reset but still this strange independent boiler heating will restart and continue. Thanks for your thoughts on this.

    heatingforce says 26th March 2018

    Hi John. I’d start with the timer/stat as it’s the easiest, but this could be a tonne of things that are hard to diagnose without being there. So, I’d call an engineer.

Nigel C says 24th March 2018

I have a Worcester Bosch Greenstar 40CDi Conventional Boiler which was installed in 2010 (nearly 8 years old). Until recently I have had no problems. This winter I started to notice that the central heating was taking a long time to heat up in the mornings. The system would be alright for days and then suddenly there would be a day when it would be delayed. This has become more frequent. This week the boiler failed in this way on two days but worked perfectly for five.
When the boiler does not heat up it does not show an error code but it does show a symbol – 2 opposite corners highlighted. This indicates that the boiler thinks the heat exchanger is warming up too quickly and as a result it shuts down for a short while and then tries again. It always seems to be at about 20-30 degrees C. Eventually it gets past 30-32 degrees C and the full ignition process completes and the boiler appears to run normally.
I have done all the recommended checks and eventually replaced my Grunfoss pump which was more than 20 years old in a last desperate hope that this would solve the problem.
Sadly this does not seem to have fixed it..
My assumption therefore is that the boiler has developed a fault and I have placed a service request with Worcester Bosch to check it out. Due to the recent cold weather they have not yet been able to arrange a visit.
What I don’t understand is that when the boiler gets up to temperature – 70 degrees C – it seems to keep going all day without a problem. This would suggest that there are no blockages in the system internal or external to the boiler.
Can anybody tell me whether they have had a similar problem and if so what was the solution?
Thank you.

Terri says 12th April 2018

I have the greenstar 25si/30si combi and it’s making a really loud rumberling noise and a dripping sort of noise I’ve turned it off at the mains do you have any idea what this is thankyou

    heatingforce says 28th April 2018

    Hi Terri. If you visit this link and scroll down there’s a section on noisy boilers, pipes, radiators etc:

Mark says 26th April 2018

Hello am having trouble with greenstar cdi the hot water will go cold when in the shower can you help please

    heatingforce says 28th April 2018

    Hi Mark, what shower is it? And which CDI do you have?

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