Seeing a fault code on your Worcester boiler can be stressful, especially when you suddenly have no heating or hot water. Knowing what the code means and what steps you can safely take helps you respond quickly and confidently. This way, you avoid causing damage to your boiler or putting your home and family at risk. Acting promptly also means you can get your heating back on sooner by contacting a qualified engineer when needed.
Safety first: Gas Safe repairs only
Anything involving gas supply, combustion, internal wiring or removing the boiler case must only be done by a Gas Safe registered engineer. As a homeowner, you should not take the cover off, poke around inside, or try to bypass any safety devices.
You can safely check things like your thermostat settings, your fuse spur, your pressure gauge, and whether other gas appliances are working. You can also usually perform a single reset if your manufacturer instructions allow it. If a code keeps coming back, the boiler locks out repeatedly, or you smell gas, switch off the appliance and call an engineer immediately.
Finding your Worcester boiler model and display
Worcester Bosch boilers have used different displays over the years, including simple lights, small digital screens and newer text displays. Knowing your exact model and display type makes it easier to match fault codes and follow the correct manual.
The model number is usually on a data plate:
Behind the drop-down flap at the front of the boiler
On the underside of the boiler casing
In your benchmark log book or installation manual
Common model names include Greenstar, Junior, CDI, CDI Compact and I Series. Once you have the model, you can look up the official manual online, or share it with your engineer so they can identify the exact fault more quickly.
Common Worcester boiler fault codes and what they mean
Below are some of the most frequently seen Worcester Bosch fault codes, explained in plain English. Exact meanings can vary slightly by model, so always refer to your manual as well.
Ignition and flame failure codes (EA, 227, D5)
EA and related codes usually point to an issue with ignition or the flame not being detected properly. This might mean the gas is not lighting reliably, the flame sensor is dirty or faulty, or there is an issue with gas supply or the burner.
Safe checks you can do: Make sure there is gas to the property by checking another gas appliance if you have one, such as a hob. Confirm the boiler has power, the room thermostat is turned up, and any programmer or timer is calling for heat. If your instructions say it is safe, try a single reset of the boiler.
Call an engineer immediately if: The EA code comes back after a reset, you smell gas, the boiler is making loud banging or whooshing noises, or the burner lights and goes out repeatedly. Ignition issues involve gas and combustion, so they must be checked by a Gas Safe engineer.
Low system pressure and water-related codes (E9, 224, 101)
Many Worcester codes relate to low water pressure or circulation problems. For sealed systems, the pressure gauge should usually read around 1.0 to 1.5 bar when cold. If it keeps dropping, the boiler may lock out to protect itself.
Typical low-pressure or water-related codes include: E9, 224, 101 and some flashing pressure symbols on newer models. These can be caused by small leaks, recently bled radiators, or faults with internal components such as the expansion vessel.
Safe checks you can do: Look at the pressure gauge on the front of the boiler and note the reading. Walk around your home and check for obvious signs of leaks on visible pipework and radiators. If the pressure keeps dropping, read our guide on boiler pressure keeps dropping for more detail on common causes and safe next steps.
Call an engineer immediately if: The pressure is repeatedly falling to zero, you can see water leaking from the boiler or pipework, or low-pressure codes appear again soon after topping up. Do not keep topping up a leaking system, as this can cause further damage and internal corrosion.
Flow and return temperature issues (CE, C6, 9U)
These codes usually suggest that water is not circulating properly through the boiler and heating system, or that temperatures are not behaving as expected. This can be due to a stuck pump, sludge in the system, or closed valves.
Safe checks you can do: Feel accessible radiators once it is safe to touch them. If several are cold at the bottom or only warm at the top, circulation may be poor. You can read more about these symptoms in our radiators cold at the bottom article.
Call an engineer immediately if: The boiler is regularly overheating, switching off, or you hear loud kettling noises. These problems are often linked to internal blockages or pump faults that need professional attention.
Fan and flue-related codes (C6, D1, 202)
Fan and flue codes indicate that combustion gases might not be moving through the boiler and out of the property correctly. The boiler has safety checks to monitor this, and will shut down if something is not right.
Safe checks you can do: From ground level, and without using ladders, you can visually check that the flue terminal is not obviously blocked by debris, leaves or snow. Do not attempt to remove or dismantle any part of the flue or casing.
Call an engineer immediately if: Fan or flue codes keep appearing, the boiler repeatedly locks out, or you notice sooting, staining or unusual smells near the boiler. Flue issues are a serious safety matter and must be inspected by a Gas Safe engineer.
Sensor and temperature probe faults (E5, E2, 297)
Sensors monitor temperature and other readings to keep your Worcester boiler working safely. If a sensor fails or gives odd readings, the boiler may show an error code and shut down to protect itself.
Safe checks you can do: Confirm that your controls are set correctly and that no one has recently changed advanced settings on smart thermostats. You can also check that pipes and radiators are getting warm as expected when the boiler does run.
Call an engineer immediately if: Sensor codes reappear after a reset, or the boiler cycles on and off very quickly. Replacing sensors or checking wiring involves opening the case, which must only be done by a qualified professional.
Next steps when you see a Worcester boiler fault code
When your boiler shows a code, it is helpful to take a clear photo of the display and note what was happening at the time, such as running hot water or heating. This information helps your engineer diagnose the fault more quickly.
Before you call, you can usually:
Check your electrics and ensure the boiler has power
Confirm room stats and timers are calling for heat
Look at the pressure gauge and note the reading
Perform a single reset if your manual says it is safe
If the same code returns, or the boiler locks out again soon after, it is time to book a repair rather than keep resetting. Repeated resets can mask an underlying issue and may lead to more serious damage.
Local boiler repair help in Bolton, Bury and Burnley
If you are seeing a Worcester fault code and your heating is off, book a boiler repair with a local Gas Safe engineer. Prompt attention often prevents small problems from turning into major breakdowns.
Homeowners in Bolton, Bury and Burnley can use our boiler repair service, including our dedicated Bolton boiler repair location. We work on Worcester Bosch boilers every day, so we can quickly track down the cause of fault codes and get your heating running again safely.
FAQs about Worcester boiler fault codes
Can I reset my Worcester boiler?
Most Worcester boilers have a reset function, either as a dedicated button or combined control. It is usually fine to try a single reset if your user manual confirms this. If the same code returns, do not keep resetting; call a Gas Safe engineer to investigate the cause.
What does EA code mean on a Worcester boiler?
EA on a Worcester boiler generally indicates an ignition or flame detection problem. In simple terms, the boiler tried to light but did not sense a stable flame. This can be due to gas supply issues, burner problems or faulty sensors, all of which need professional testing.
Is it safe to use my Worcester boiler with a fault code showing?
If your boiler has locked out and is showing a solid fault code, it is telling you it is not safe to run in its current state. Do not attempt to override or bypass any safety controls. Follow your manual, carry out only basic visual checks, and call a Gas Safe engineer.
Who should I call for Worcester boiler repairs?
You should always use a Gas Safe registered engineer who is experienced with Worcester Bosch appliances. If you are in Bolton, Bury or Burnley and your Worcester boiler is showing a fault code, contact JS Gas & Oil Ltd on +447791802791 to arrange a safe, professional boiler repair.
We will talk you through any simple checks over the phone, then attend promptly to diagnose the fault, source genuine or high-quality compatible parts, and get your heating and hot water back as quickly as possible.
Need Fast, Reliable Worcester Boiler Repairs? Book Now!
If your Worcester boiler is showing a fault code and your heating or hot water isn’t working, don’t delay—book a professional repair with our trusted Gas Safe engineers today. Acting quickly ensures your home stays warm and safe while preventing minor issues from turning into costly breakdowns. Homeowners in Bolton, Bury, and Burnley can count on our expert team for prompt, reliable service. Contact JS Gas & Oil Ltd on +447791802791 and visit our boiler repair page or Bolton boiler repair page to book your appointment now.
