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Worcester Bosch Boiler Troubleshooting

Experiencing problems with your Worcester Bosch boiler? As good as Worcester boilers are, they aren’t completely immune to faults. The good news is that in many cases, the issues can be resolved without the help of a professional. In this guide, we’ll explain some of the most common issues with Worcester boilers, how they can be fixed and what error codes to look out for.

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Common Worcester Bosch boiler problems

If you have a Worcester Bosch boiler installed in your home, it’s a good idea to be aware of the problems that may occur with it.

There are different models of Worcester Bosch boilers, so it’s always good to know which model you have. There is usually a label on the bottom of your boiler which details this. It is really useful to keep your boiler operating manual in a safe place as this can be used for recording your annual boiler service and also has a fault finding section which details all the boiler fault codes that apply to your particular boiler.

Some of these issues may not apply if your boiler is not a combination boiler, and sometimes, faults can be related to your heating system rather than your boiler. It’s always a good idea to get in touch with a qualified Gas Safe registered heating engineer if it’s not something simple like topping up boiler pressure.


Low Pressure 

When your boiler system is cool, check the pressure gauge. It should be between 1 and 1.5, or in the green section. Water pressure problems are common in boilers, especially for those which are old or have been in use for some time. 


Leaking Boiler 

If your Worcester boiler is leaking, make sure you deal with it as soon as possible as the longer it leaks, the greater the amount of damage it can create. This can be particularly dangerous if there are any exposed electrics near the leak. 


Boiler Lockout 

If your Worcester boiler is showing the code EA 227, this means the unit has locked out as a safety precaution. This shuts down the operations of the boiler to prevent any further damage being caused. There are a number of reasons for a boiler lockout, including incorrect pressure and blocked flue pipes. 


Banging Noises 

If your Worcester boiler is making noises, it will most likely be caused by kettling. This is caused by a drop in water pressure, limescale build-up or a faulty thermostat. The banging noise should be addressed as soon as possible, since if it is left unattended, it can cause wider issues. 


Overheating Boiler 

Your Worcester boiler may overheat due to a faulty pump or fan, a blocked condensate pipe or due to limescale. These causes can usually be quickly identified by a heating engineer.

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Why is my Worcester boiler not firing up?

There are many reasons why your Worcester boiler may not be firing up, but the most common reasons are due to gas supply, ignition or an inability to operate safely. 


If there is an insufficient gas supply, the ignition electrodes are faulty or the burner is blocked, your boiler will fail to fire up. 


Other reasons why your boiler may not be able to operate safely include frozen condensate pipes, clogged flue pipes or faulty fans. It will remain locked until the root issue is resolved. 


In a lot of cases, it’s best to have a Gas Safe engineer to fix the issue for you. 


How do I reset my Worcester Bosch boiler?

Most Worcester Bosch boilers are relatively straightforward to reset, and all you need to do is press and hold a button for 3-5 seconds. The reset button is typically located on the boiler control panel. You can refer to the boiler manual if you are struggling to figure out how to reset your boiler.


Resetting your Worcester boiler will not fix the fault that caused it to lock out in the first place, and you should only reset your boiler once the issue has been resolved. 


Why is my Worcester boiler firing but there is no hot water?

If your Worcester boiler is firing up but there is no hot water, there are a few potential issues that could be causing this. However, one of the most common issues is a faulty diverter valve. 


The diverter valve’s job is to control the flow of hot water and divert it to your water outlets and your central heating. However, the diverter valve can become worn, resulting in the valve only partially opening meaning the water flow is negatively affected. This results in cold or lukewarm water flowing, instead of hot water. 


You will need to call out a Gas Safe engineer to fix this issue as it could be causing other internal issues. 


How do I fix the pressure on my Worcester boiler?

Low water pressure is a sign that the water needs topping up in your Worcester boiler, or that you may have a leak. You will see the code 1017W if you have low water pressure.


When your boiler reaches below a certain pressure, it will lock out. To fix this, you will need to repressurise it by using the external filling loop. To find out more on understanding boiler pressure, read our dedicated guide.


Once you’ve corrected the pressure, reset your boiler following the steps previously outlined. If the issue still persists, you may have a leak and again will need to enlist the help of a professional heating engineer. 


Why is my Worcester boiler light flashing?

A flashing light on your Worcester boiler can indicate that connections need to be checked. 


A slow flashing on a Worcester boiler that goes on for two pulses indicates that you need to check the service mode switch as it is in the minimum position. 


Fast flashing will indicate that the code plug is blocked. To fix this, reset your boiler as this will restart your heating system. 


Sometimes flashing lights will indicate small issues that can be fixed at home. However, if you’re unsure about investigating yourself, it’s always a good idea to get an engineer to check for you.

How to adjust the flow temperature on a Worcester Bosch boiler

The process of adjusting the flow temperature can vary from model to model. In general, the control can be located on the control panel of each Worcester model. 


To adjust the flow temperature, simply adjust the thermostat on the boiler by turning the dial or using the digital display.

How do I find the error codes on my Worcester boiler?

Finding the error codes on your Worcester boiler is relatively straightforward. When an error occurs, the boiler’s control panel will show a specific code. This code is an indication of what the problem is. 


You can find the cause code by pressing the spanner or return button, which will display a three digit number, which is the specific error code. 

Worcester Bosch boiler error codes

There are a number of error codes that may show on your boiler. Listed below are some common codes which you may see:


  • Fan speed error: C6 215
  • Heat control module: 9A 362
  • No flame signal due to blockage or internal leak: EA 227
  • Blocked pump: A1 281 
  • Minimum burner load: EF 349
  • Flow temperature high: No code 212
  • Loss of ionisation: EA 229
  • Flow temperature too high: E5 218
  • Sensor too high: 2964 B
  • Low water pressure: 1017 W
  • Safety sensor code: 226
  • Internal error: F0 237
  • Potential control board problem: B7 257


As mentioned previously, each model will have its own variety of error codes as well, so it’s always a good idea to keep your user manual just in case an error code occurs which isn’t on our list.

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