Worcester Bosch boilers covered
Worcester Bosch is one of the most widely fitted boiler brands in the UK, and most homes with one of its boilers will have a model from the Greenstar family. The guidance on this page applies to the main Greenstar ranges you are likely to find:
- Greenstar i, a compact combi that has been fitted in large numbers since the early 2010s.
- Greenstar Si, another popular combi, often found in flats and smaller houses.
- Greenstar 4000, the current mid-range combi and system boiler range.
- Greenstar 8000 Life, the premium range with a larger colour display.
Older Greenstar models, such as the Junior and some early CDi boilers, work in a similar way, although their displays and controls are simpler.
How fault codes appear on a Greenstar
On most Greenstar models a fault is shown as two parts. The first is a two-letter display code, such as EA or CE. The second is a three or four digit cause code, such as 227 or 207, which pins down the exact reason. Together they read as EA 227 or CE 207.
On some models the display switches between the two parts, so you may see "EA" and then "227" a moment later. Note both parts down before you do anything else, because the cause code is what an engineer will ask for. On the 8000 Life the code usually appears alongside a short text description.
The blue light on some older models
Some older Worcester boilers have a blue indicator light on the front panel. On these models a flashing blue light usually means the boiler has locked out and needs attention, while a steady blue light normally shows the burner is running. The exact behaviour differs between models, so check the user manual for yours.
How to reset a Worcester Bosch boiler safely
Most Greenstar boilers have a reset button on the front control panel. On many models you press and hold it for a few seconds until the display changes, while some older boilers are reset by turning the temperature knob to a reset position. Your manual will confirm the method.
Only reset after you have dealt with any obvious cause, such as low pressure or a frozen condensate pipe. If the code returns after 2 or 3 attempts, stop and call a Gas Safe registered engineer. Repeated resets will not fix an internal fault.
Checking the pressure gauge
Every Greenstar has a pressure gauge, either a dial under the boiler or a reading on the display. With the heating cold it should normally sit between 1 and 1.5 bar. Below that the boiler may show CE 207. Our guide on how to repressurise a boiler explains how to use the filling link or filling loop safely.
Common winter faults
In cold weather the most common Worcester Bosch problem is a frozen condensate pipe, which often leads to EA 227. If the pipe running outside from the boiler is frozen, thaw it with warm (not boiling) water, then reset. See our frozen condensate pipe guide for the full steps.
If you smell gas, turn off the gas at the meter if it is safe to do so, open windows and call the National Gas Emergency Service on 0800 111 999. Do not use light switches or naked flames.
When to call a Gas Safe engineer
Never remove the boiler casing. Anything inside the boiler, including the gas valve, electrodes, fan and circuit board, must be checked by a Gas Safe registered engineer. Call one if a code keeps coming back, if you need to top up the pressure often, or if you notice water leaking from the boiler.