Call us on:

0203 504 4000

× Services Areas We Cover Guarantee Rates About Us Feedback Accreditations Blog Contact

Common Worcester Boiler Problems


Lee Devlin

Published on: 02/10/2020
Card 3 image

If you have a Worcester Bosch boiler installed in your home it is a good idea to be aware of some of the common problems they experience. Most, but not all, boiler breakdowns require you to call out an engineer and once you understand some of the typical error codes and faults that may appear, it can save you time and money.

We’ve put together a comprehensive guide to the most common Worcester boiler problems and fixes to give you more insight. So no matter what issue your boiler has, you can rely on Homecure’s Worcester boiler troubleshooting expertise to get everything back to normal as quickly as possible.

Top 10 Worcester Bosch Boiler Problems

1. Low boiler pressure

When the system is cool, the pressure gauge on a Worcester boiler should be between 1 – 1.5 (in the green section). Worcester boiler water pressure issues are common, especially for those that have been in use for some time. When water pressure is low on a Worcester boiler it can potentially damage the system and stop it from working properly.

2. Leaking boiler

A leaking Worcester boiler should be dealt with quickly, as the longer the leak continues, the more damage it can create. This is especially true of any electrical parts that may be exposed to the water, which is both dangerous and can potentially lead to expensive boiler repairs.

3. Banging noises

More often than not, Worcester Bosch boiler problems that create noises will be due to kettling. This is a consequence of a drop in water pressure, limescale build-up, or a faulty thermostat. A Worcester boiler making noise should be addressed as soon as possible as if left unattended it can also create wider issues in the system.

4. Boiler lockout

Worcester boilers with error 227 codes mean the unit has locked out as a safety precaution. This shuts down its operation to prevent any further damage being caused. There can be any number of reasons for this to happen, from blocked flues to high or low boiler pressure.

5. Blocked condensate pipe

Worcester Bosch boilers feature a condensing pipe, which vents harmful gases away from your property. Owners do sometimes experience a blocked condensate pipe during the colder months of the year, but this can be easily fixed with warm water.

6. Overheating boiler

You Worcester boiler could overheat because of a faulty pump or fan, a blocked condensate pipe or due to excessive limescale on the heat exchanger. The cause can be quickly identified and resolved by an experienced engineer.

7. No power

If the boiler has lost all power it could be because of a faulty electronic control board, a tripped spur socket or residual current device (RCD). Where it’s an issue with a control board, it may prove more cost-effective to opt for a new boiler installation, although this varies from case-to-case.

8. No hot water

Worcester boiler problems with no hot water is a common problem and one that could be caused by a number of different things. This could be anything from a faulty diverter or Y/S-plan valve, or issues with the PCB unit or heating pump. For example, dirt and grit that has passed through the mesh of  flow turbine of a Worcester Junior 28i Combi boiler can

9. Radiators not heating up

Worcester boiler problems with no heating can often be resolved quite easily. If there is a build-up of air or sludge in the system it could be the reason why you are not getting the most out of your radiators. This will need them to be bled which can be done with a radiator key without an engineer. Some cases may require a flush out to clear the system but this is not often the case.

10. Boiler turns itself off

Low water pressure, thermostat issues or a closed valve causing water flow issues could be the reason why your boiler repeatedly switches itself off. Boiler servicing by a reputable company will be able to diagnose the cause and offer a solution that stops this from occurring.

Which Worcester boiler problems need a Homecure engineer?

Homecure engineers have years of experience dealing with Worcester boiler repairs and can fix a wide range of issues. Common problems we can help with include:

Boiler issuePossible reasonShould I call a Homecure engineer?
No heating or hot waterLow water levels, faulty thermostat, broken airlocks or diaphragmsYes
Banging or whistling noisesKettling (limescale build-up), air in system, low water pressureYes
Faulty pilot lightBroken thermocouple affecting gas supplyYes
Leaking boilerFaulty boiler component or broken pipingYes
Low water pressureWater leak, broken pressure relief valve, recently bled radiatorsYes – but only in the case of a leak
KettlingBuild-up of sludge or limescale on the heat exchanger causing banging noisesYes
Boiler constantly turns offBroken thermostat, water pressure or water flow issues, or pump circulation problemsYes
Faulty thermostatCould be due to incorrect settings or not being turned onYes – if unable to resolve with settings
Unevenly heated radiatorsBuild-up of sludge or air causing blockages and distribution of air to radiatorsYes – if bleeding the radiators doesn’t work
Boiler lockoutLow water pressure, blocked flues – there are a number of possible reasonsYes – if resetting the boiler does not work.

Our team at Homecure offers a range of services across a number of other brands, including boiler repairs for Vaillant, Glow Worm and Baxi.

Worcester Bosch boiler error codes

Your Worcester Bosch boiler will typically display an error code when there is a problem that needs to be fixed. Not all error codes mean the same thing on different systems, so it is always a good idea to refer to the boiler manual if unsure. Below we’ve listed some of the most common error codes for a range of Worcester Bosch boilers.

BoilerError CodeBoiler Issue
CDI Classic CombiA1Water leak or new pump required
CDI Highflow CombiD5Condensate pump failure
CDi Compact / Greenstar 25/30 Si Combi / Greenstar 27/30C7 214Fan not in operation
CDi Classic RegularEAFlame not detected
Greenstar I System / Combi BoilerE9 224Flue or high limit thermostat activated
GB162 Boiler203The boiler is on standby
CDI Highflow Combi3 flashes 5 seconds offGas valve error
Greenstar Ri BoilerSlow flash (mostly off)Ignition lockout
Greenstar 8000202 OBoiler in anti-cycle mode
Combi, regular and system oil boilersRed steady onLockout

FAQs about Worcester boiler problems

How do I reset my Worcester boiler?

Reset instructions will vary from model to model. For example, to reset a Worcester Bosch Greenstar boiler you press the reset button for 3 seconds, which stops the reset button and fault indicator from flashing. Refer to the boiler manual for full instructions for your model.

Why does my Worcester boiler keep cutting out?

There can be a number of reasons why your Worcester boiler keeps cutting out. It may be because of a faulty component, a drop in water pressure, or due to overheating. This lockout is designed to protect the overall system. Our engineers can quickly identify the issue and apply a cost-effective resolution.

How do I fix the pressure on my Worcester boiler?

By using the external filling loop you can increase the pressure in your boiler. However, if the issue is related to a leak, this should be dealt with as soon as possible by a qualified engineer. If unsure the cause of the issue is due to a leak, and if the pressure continues to drop, it is likely to be due to a leak.

Why has my Worcester boiler stopped working?

If your Worcester boiler has stopped working it can be extremely concerning and stressful. There are a number of reasons why this may have happened. For example, a CDI Classic Combi boiler may need a new pump, or a  CDI Highflow Combi could have an issue with a condensate pipe. This is something our qualified engineers can identify and resolve in no time at all.

Why is my Worcester boiler light flashing?

The flashing blue light on your boiler could be caused by issues with a gas supply (error code EA), or linked to low boiler pressure (error code CE 207). A pulsing, rather than flashing, light on an Greenstar Ri boiler means it is in service mode. If you are unable to identify and resolve the issue a Homecure engineer will be able to assist.

How do I reset my Worcester 28cdi boiler?

In order to reset the Worcester 28cdi boiler you must press the reset button and hold it in position for 5 seconds. You may be required to do this if the boiler has experienced a lockout or you see a flashing light display. Always refer to the boiler manual if you are unsure of the reset procedure.

How do you get air out of a Worcester boiler?

When air is stuck in a Worcester boiler it will lockout and you will hear a gurgling sound inside the pipes. This can lead to the pressure dropping in the system. Ideally, the pressure bar should sit between 1 and 1.5 and you can use the internal filling loops to repressurise the system and get it back into operation.

Why does my Worcester Bosch boiler keep losing pressure?

Over time, all boilers naturally lose pressure. However, if you experience a sudden drop this could be due to a fault with the system. Often this is associated with a leak, so if you use the internal filling loop to increase the pressure and it drops again soon after, you should call an engineer to investigate.


Lee Devlin
Publication date: 02/10/2020

Lee Devlin is the managing director of Homecure Plumbers, London's favourite local plumbing service. Since 2009, Lee's been leading a large team of gas safe plumbing and heating engineers as well as growing a successful business built on quality customer service and workmanship, in a competitive industry within the Capital. He's been in the game for a long time, so he regularly shares his knowledge and experience with the public. His expert tips have been featured in lots of well known publications such as: The Sun, Metro, Insider, Homes And Gardens, Country Living and more!

Read More About Lee Devlin.

reviews on Google
Very good
I had a good experience with this service. Terry who came out to see my issue was very good and professional.
Homecure attended my boiler very promptly diagnosed the fault and were proactive in sourcing the relevant part and getting it going again straightaway
Really good service, completed in a professional manner and to an excellent standard.
I would highly recommend and use again.
I have been using Homecure for years now, they are always professional and helpful. They were quick to respond to an emergency with some plumbing issues when I moved into my new house and I always use them for my boiler services and maintenance. I highly recommend this company.
Fixed our issue very swiftly with a great professional and friendly service. Would recommend and will be using again!
David is extremely thorough and knowledgeable in his field. He has maintained and serviced our boiler for 3 years now. Dave is reliable, polite, personable and very tidy in his work. I would wholeheartedly recommend his services.