Are you fed up with your heating system malfunctioning? Are you constantly topping up the water in your boiler, yet the boiler pressure continues to drop. As the original leak detection company in the UK, we are regularly called out to locate the source of a leak, but in many cases, your heating system does not have a leak, and it is a different problem. The good news is that modern Worcester Bosch boilers even tell you what the problem is, even if the boiler pressure is too high – the challenge is deciphering what the boiler is trying to tell you so that you can call the right company to fix it, or even better deal with the issue yourself.

ADI is a leak detection company with integrity and honesty. We are confident that we are the best company in the UK at resolving your leak detection problems, but we are also committed to saving our customers money and helping them resolve their issues as quickly as possible. As part of our commitment to customers, we have compiled a list of the most common Worcester Bosch boiler codes and explained them in everyday English for your convenience. 

We understand the worry that people go through when their healing system develops a fault, and it is almost inevitable that this will be during the winter period when a warm and cost home is vital. With the help of the guide below, you should be able to quickly and easily identify and understand what the boiler is trying to tell you, and then perhaps just as importantly understand who to call to solve the issue. 

Error Codes Related To A leak On The Boiler Or Central Heating Pipework

Worcester Bosch CDi Classic Regular Boiler Error Codes

Code Error  English Explanation 
B1 Code Plug Not Detected A code plug is a very small printed circuit board about the size of  a sim card. This error requires the expertise of a boiler engineer or fitter
C6 Fan Speed Too Low  The reason why the fan speed can be too low could be any number of reasons, including the PCB, the fan assembly, or the fan harness. Call your local boiler engineer, this is a job for a professional. 
E2 Central heating (CH) flow negative thermistor coefficient (NTC) sensor defective This needs a replacement sensor fitted, – Boiler Engineer 
E9 Safety temperature limiter in central heating (CH) flow has tripped This could be an issue where the system needs to be bled which is an easy process, however if that does not resolve it then it will need a boiler engineer. 
EA Flame not detected The good news here is that it even though there is no flames detected it does not mean that the boiler is leaking gas everywhere. This code is actually a safety process to stop any leaks occurring. Check that you have gas, there could be a problem with your gas supply. If you have other gas appliances such as a cooker are they working? If everything else appears to be working contact your gas supplier free of charge first to check there is no issue with the supply. If the gas is working according to the supplier, or because you gas cooker is working, then contact a boiler engineer. 
FO Internal Error This could be an issue with the  electrical connector contacts or programmer interface module. If you feel confident you could check that your ignition leads are not loose, but unfortunately this might need the services of a boiler engineer. 
F7 Flame detected even though appliance switched off Check the electrode assembly is dry and also that the pcb and flue are clear.
FA Flame detected after gas shut off Your gas valve needs to be checked. You need to contact a gas safe installer
FD Reset Button Pressed By Mistake  Quick and easy, simply press the reset button again. 

Worcestershire Bosch CDI Highflow Combi Boiler Error Codes 

A1 Pump dry run detection or pump is running in air the system pressure needs checking This could be as a result of a water leak. If you top up the pressure and the fault reappears within a short space of time, contact ADI to come and find the source of your leak. 
A5 Tank Negative Thermistor Coefficient (NTC) defect Contact a local boiler engineer. 
A7 Domestic hot water (DHW) negative thermistor coefficient (NTC) defect Contact a local boiler engineer
A8 Energy Management System (EMS) communication error Contact a local boiler engineer 
B1 Code Plug Not Detected A code plug is a very small printed circuit board about the size of  a sim card. This error requires the expertise of a boiler engineer or fitter
B2,B3,B4,B5,B6 Data Error  Try pressing the reset button, but if this does not work then contact a boiler engineer
B7 Burner Control Error  Contact A Boiler Engineer 
C6 Fan Speed Too Low  The Fan Lead and Connector Need To Be Checked, and Could Need To Be Replaced.
D3 External Temperature Limiter  Contact A Boiler Engineer
D5 Condensate Pump Failure Contact A Boiler Engineer
D6 Internal Heat Bank Overflow  Contact A Boiler Engineer
E2 Primary negative thermistor coefficient (NTC) defect Contact A Boiler Engineer
E9 Safety temperature limiter in central heating (CH) flow stat tripped Contact A Boiler Engineer
EA Flame Not Detected  Check your gas and power supply. Additionally your igniter, electrode and leads all need to be checked by a Gas Safe Installer
F0  Internal Error  This could be an issue with the electrical contacts, or programmer interface module – check to ensure that the ignition leads are not loose, and then call a Gas Safe Engineer. 
F1 ROM Fault  Contact A Boiler Engineer
F7 Flame detected after appliance has been shut off Contact A Boiler Engineer
FA Flame Detected After Gas Shut Off  Contact A Boiler Engineer
FD Reset Button Pressed By Mistake Quick and Easy Fix, Press The Reset Button Again 

Generally speaking, there are three main options when it comes to boiler and central heating issues. Depending on your competence level, certain issues can be rectified yourself, such as when the reset button has been pressed by accident, or the water pressure has dropped slightly, and the system needs to be topped up. 

The second option relates to boiler issues, in which case we would almost always recommend you contact a professional boiler engineer. Gas boilers are not something to take a risk with, and it is potentially very dangerous to work on a boiler without the relevant knowledge, training, or expertise. 

The one exception to this is when it comes to leak detection. Leaks happen regularly in a central heating system, mainly because the joints are always expanding or contracting as the central heating system works. Most homeowners automatically assume that their local plumber or boiler engineer is the person to contact when this problem arises, but the reality is that leak detection is a very specialized niche. It requires knowledge and specialist tools, which most plumbers do not have. 

As the original leak detection company in the UK, ADI are the experts and market leaders when it comes to leak detection. We publish lots of boiler advice including various fault code information to help you find the solution to your boiler problems. We can find your leak, quickly and easily. And perhaps most importantly of all, we do not need to cause unnecessary damage in the process, which is the thing our customer’s value and appreciate. If you believe that you have a leak in your central heating system call us on 0800 731 3843

Watch the video below to understand how we find your leak using non invasive leak detection equipment..

Water Leak Detection Services UK - Leak Detection London

Call Our Team On 0800 731 3843 If You Believe A Hidden Water Leak Is Causing Your Worcester Bosch Boiler To Display A Fault Code.