Work Guaranteed
Same Day Service
Established in 2009
Certified Engineers
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 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.
When the system is cool, the pressure gauge on a Worcester boiler should be between 1 – 1.5 (in the green section). Low pressure is common, especially on boilers 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.
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.
More often than not, Worcester Bosch boiler problems that create noises will be due to kettling. This is caused by limescale, sludge or poor circulation through the heat exchanger. 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.
Worcester boilers showing error 227 have locked out because no flame was detected when the boiler tried to light. It shuts down as a safety precaution. Common causes are a frozen condensate pipe, a problem with the gas supply or worn ignition or flame sensing electrodes.
Worcester Bosch boilers have a plastic condensate pipe that drains the mildly acidic water the boiler produces away to a drain. Owners do sometimes find it frozen or blocked during the colder months of the year. A frozen pipe can usually be thawed by pouring warm (not boiling) water over the outside section.
Your 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.
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.
No hot water is a common Worcester fault, and it can have a number of different causes. 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 block it, so the boiler no longer senses when a hot tap is turned on.
Radiators that won’t heat up can often be sorted 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.
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.
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 pressure, faulty thermostat, airlocks, faulty motorised valves, or failed diverter components | Yes |
| Banging or whistling noises | Kettling (limescale or sludge on the heat exchanger), air in the system | 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.
On most Greenstar boilers, press and hold the reset button for about 3 seconds. Check the manual for your model. If it locks out again, note the code on the display rather than resetting it over and over.
A slow drop usually means a leak in the system, or a faulty pressure relief valve or expansion vessel. Top it up to between 1 and 1.5 bar with the filling loop (see how to repressurise a boiler). If it drops again within a few days, book an engineer.
A flashing light with a code on the display means the boiler has locked out. EA codes point to an ignition problem, often the gas supply or a frozen condensate pipe (see our EA 227 guide). On Greenstar boilers, low pressure usually shows as a flashing blue light, with CE / 1017 or 207 on the display.
Once a year. Worcester Bosch warranties of up to 12 years, depending on model, need a yearly service by a Gas Safe engineer. See our boiler servicing.
Most modern Worcester Bosch boilers in the Greenstar and CDi ranges show a fault code on the display when they lock out. The code points to the part of the system that has a problem, which makes diagnosis much quicker. The table below explains the most common Worcester Bosch fault codes and their likely causes. Exact codes can vary by model, so always check your user manual, and remember that anything involving gas, ignition or the sealed unit must be handled by a Gas Safe registered engineer.
| Code | What it means | Likely cause |
|---|---|---|
| EA / 227 | No flame detected (ignition lockout) | Gas supply turned off, a faulty ignition electrode, a frozen or blocked condensate pipe, or a gas valve fault |
| 229 | Repeated failed ignition, boiler locked out | The boiler tried to light several times and stopped for safety, usually the same causes as EA |
| E9 | Overheat, safety temperature limiter tripped | Poor circulation, a faulty pump, a stuck zone valve or a blocked heat exchanger |
| CE / 1017 | Low water pressure | System pressure has dropped below about 1 bar, often a small leak or after bleeding radiators. Repressurise to 1.0 to 1.5 bar |
| C6 | Fan running at the wrong speed or not at all | Fan fault, a wiring problem, or a blocked flue or condensate pipe |
| C7 | Fan not running (no fan signal) | A failed fan, which usually needs replacing |
| A1 | Pump stuck, running dry or poor circulation | Low pressure, trapped air, a seized pump or a blockage in the system |
| E2 | Flow temperature sensor fault | The NTC flow sensor is misreading or has a wiring fault |
| D1 | Temperature sensor fault (flow or return) | A short circuit or broken connection on an NTC sensor |
| F7 | False flame signal detected | The board is sensing a flame when there should not be one, often the ionisation electrode |
| FA | Flame detected after the gas valve has closed | The gas valve is not closing fully or an electrode fault, a safety critical gas fault |
| FD | Reset button pressed by mistake or stuck | A stuck reset button or an accidental reset |
| F0 | Internal control board fault | A defect on the PCB or its wiring |
| A21 / A7 | Lost communication with the wireless thermostat | The room thermostat or controller has lost its signal or has flat batteries |
A one off code can sometimes be cleared with a single reset. If the same code keeps returning, do not keep resetting the boiler, as repeated resets on a gas fault are unsafe. Book a Gas Safe engineer to find and fix the underlying cause. Our boiler repair team works with all Worcester Bosch models and can attend the same day for a boiler breakdown.
From the job: Greenstar 30i showing EA 227 after a cold night
Worcester Greenstar 30i showing EA 227. Checked the condensate pipe first and it had frozen where it drops down the outside wall. Thawed it with warm water, reset the boiler, then lagged the outside run.
Expert notes by Jamie Watkins, Gas Safe registered engineer (Gas Safe ID 6115118), Homecure Plumbers – Gas Safe Reg 505421
From the job: Greenstar 4000 dropping to CE 1017
Greenstar 4000 combi kept dropping to CE 1017 every few days. Found a weeping compression joint on a radiator valve behind the sofa. Remade the joint, topped the system back up and it’s held pressure since.
Expert notes by Kevin Saban, Gas Safe registered engineer (Gas Safe ID 6115119), Homecure Plumbers – Gas Safe Reg 505421
See our Worcester boiler repairs page or call 0203 504 4000. Repairs from £95 + VAT for the first hour, including diagnosis (or a fix if it can be done within the first hour with no parts needed), no callout charge. Prices apply during office hours; parking or the congestion charge may be added.