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 issue | Possible reason | Should I call a Homecure engineer? |
| No heating or hot water | Low water levels, faulty thermostat, broken airlocks or diaphragms | Yes |
| Banging or whistling noises | Kettling (limescale build-up), air in system, low water pressure | Yes |
| Faulty pilot light | Broken thermocouple affecting gas supply | Yes |
| Leaking boiler | Faulty boiler component or broken piping | Yes |
| Low water pressure | Water leak, broken pressure relief valve, recently bled radiators | Yes – but only in the case of a leak |
| Kettling | Build-up of sludge or limescale on the heat exchanger causing banging noises | Yes |
| Boiler constantly turns off | Broken thermostat, water pressure or water flow issues, or pump circulation problems | Yes |
| Faulty thermostat | Could be due to incorrect settings or not being turned on | Yes – if unable to resolve with settings |
| Unevenly heated radiators | Build-up of sludge or air causing blockages and distribution of air to radiators | Yes – if bleeding the radiators doesn’t work |
| Boiler lockout | Low water pressure, blocked flues – there are a number of possible reasons | Yes – 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.
| Boiler | Error Code | Boiler Issue |
| CDI Classic Combi | A1 | Water leak or new pump required |
| CDI Highflow Combi | D5 | Condensate pump failure |
| CDi Compact / Greenstar 25/30 Si Combi / Greenstar 27/30 | C7 214 | Fan not in operation |
| CDi Classic Regular | EA | Flame not detected |
| Greenstar I System / Combi Boiler | E9 224 | Flue or high limit thermostat activated |
| GB162 Boiler | 203 | The boiler is on standby |
| CDI Highflow Combi | 3 flashes 5 seconds off | Gas valve error |
| Greenstar Ri Boiler | Slow flash (mostly off) | Ignition lockout |
| Greenstar 8000 | 202 O | Boiler in anti-cycle mode |
| Combi, regular and system oil boilers | Red steady on | Lockout |
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.
