Worcester Bosch boilers
Worcester Bosch is one of the most common boiler brands in UK homes. The company began in Worcester, England, in 1962. It is now part of the Bosch Group, the large German engineering firm.
Most Worcester gas boilers carry the Greenstar name. Newer models add a number, such as 2000, 4000 or 8000. Other models use letters instead, like Si, CDi and Ri. You’ll find the full name on the front of the boiler or on its data label.
How Worcester Bosch boilers show a fault
Many Greenstar boilers with a screen show a fault in two parts. First comes a short code, such as EA. Under it is a three-digit number, such as 227, which gives more detail. Worcester’s user guides show it this way. So when people search for “EA 227”, they mean this pair of codes.
Some older Worcester boilers have no screen. They show faults with lights instead. Your user guide explains what each light pattern means for your model.
The most common winter problem
In cold weather, many Worcester boilers stop because the condensate pipe has frozen. This is the small plastic pipe that runs outside to a drain. Worcester says you may hear a gurgling noise, and the screen may show EA. The fix is often simple and safe to do yourself. Our guide shows how to thaw a frozen condensate pipe.
Before you call an engineer
A few checks can save you a call-out:
- Is the pressure gauge between 1 and 1.5 bar when the boiler is cold? If not, see how to top up low boiler pressure.
- Do your other gas appliances work, such as the hob? If not, the problem may be your gas supply.
- If you have a prepayment meter, is there credit on it?
- Is the condensate pipe outside frozen?
If the boiler still won’t work after a reset, call a Gas Safe registered engineer. Tell them the full model name and the code on the screen. It helps them bring the right parts.
Worcester Bosch gas boiler ranges
These are the gas boiler ranges on the Worcester Bosch website as of 21/10/2026.
- Greenstar 1000
- Greenstar 2000
- Greenstar 4000
- Greenstar 4000 System System
- Greenstar 8000
- Greenstar CDi Compact
- Greenstar i System Compact System
- Greenstar Ri Regular
Older Worcester Bosch ranges
You may still find these in homes. They are no longer sold new, but many are still working.
- Greenstar i Junior
- Greenstar Si
- Greenstar CDi Classic
- Greenstar 8000 Life
- Greenstar 8000 Style
Common Worcester Bosch fault codes
Codes can differ between models and ages of boiler. Always check the user manual for your exact model.
| Code | What it means | What you can do |
|---|---|---|
EA | Worcester Bosch links this code to a frozen condensate pipe. You may also hear a gurgling noise from the boiler. | Thaw the pipe outside with warm water (never boiling), then reset the boiler. If the code comes back, call a Gas Safe engineer. |
Worcester Bosch manuals
Worcester Bosch puts its user guides and installation manuals on its own website. You can find Worcester Bosch manuals here. You'll need your model name. The GC number helps too. Our guide shows you how to find your boiler's model and GC number.
Stay safe. You can reset a boiler, top up its pressure and thaw a frozen condensate pipe yourself. Anything inside the case is a job for a Gas Safe registered engineer.
If you smell gas, leave the building and call 0800 111 999.