Glossary · Faults, servicing and gas safety
What does the EA fault code mean on a Worcester Bosch boiler?
EA is a fault code shown on the display of some Worcester Bosch boilers when the boiler repeatedly locks out or stops working. Worcester Bosch links it to a blocked condensate pipe, most often one frozen in very cold weather. Worcester says you can usually thaw the pipe safely yourself with warm water.
Key points
- Worcester Bosch says a blocked condensate pipe can make the boiler lock out repeatedly and show an EA code, often with a gurgling noise.
- Frozen condensate is a common winter problem. Worcester says you can usually thaw it safely without calling an engineer.
- Pour warm water, not boiling water, along the outdoor pipe, then reset the boiler.
- Some Worcester boilers show other signs for the same problem, such as a D5 code or a slow flashing blue light.
- If thawing does not clear the fault, or it comes back, book a Gas Safe registered engineer. Do not open the boiler casing.
What causes an EA fault
A condensing boiler produces waste water as part of normal operation. The condensate pipe carries it away. Worcester Bosch describes it as a pipe, normally plastic, that runs from the boiler to a household drain or a soakaway outside.[2]Worcester Bosch, Boiler not working in freezing temperatures? Water running through it is a sign the boiler is working normally.[2]Worcester Bosch, Boiler not working in freezing temperatures?
If part of that pipe is outside, a long spell of freezing weather can freeze it. Worcester Bosch lists two signs of a blocked condensate pipe. The boiler may gurgle when it tries to start. It may also repeatedly lock out, or stop working, and the display may show an EA code.[1]Worcester Bosch, How do I know that my condensate pipe is blocked?[2]Worcester Bosch, Boiler not working in freezing temperatures? A boiler in lockout has shut itself down and needs attention before it will run again.
The EA code does not appear on every Worcester model. Worcester says that, depending on the boiler, a frozen condensate pipe may show as an EA code, a D5 code or a blue light that flashes slowly and stays off longer than it is on.[3]Worcester Bosch, Does an external condensate pipe have to be insulated? The Worcester pages we checked link EA to the condensate pipe. They do not list other causes, so check your manual if the pipe is clear.
What you can check yourself
Worcester Bosch says frozen condensate is a common winter problem that arises in extreme weather, and that you can usually thaw the pipe safely without calling an installer or engineer.[2]Worcester Bosch, Boiler not working in freezing temperatures? Its steps are as follows.[2]Worcester Bosch, Boiler not working in freezing temperatures?
- Look for the outdoor pipe connected to your boiler. It is usually white plastic connecting to an external drain.
- If it is safe to do so, pour warm water along the pipe. Do not use boiling water.
- Reset your boiler. If the pipe has defrosted, everything should be working normally.
Take care on icy ground and do not lean from a window or ladder to reach the pipe. If you cannot reach it safely, call an engineer. Worcester also lists ways to reduce the risk of the pipe freezing again.[2]Worcester Bosch, Boiler not working in freezing temperatures?
| Measure | What Worcester says |
|---|---|
| Heating control | Turn the boiler’s heating control to maximum in freezing weather |
| Drain cover | Install a drain cover to protect the pipe end |
| Insulation | Insulate the external pipework |
| Length and size | External runs should be kept to a maximum of 3 metres and insulated on most boilers. A 32 mm pipe is advisable |
The last row comes from Worcester’s page on insulation. On a Greenstar CDi Classic or i boiler, or with a CondenseSure kit, the pipe does not need insulating if it is 32 mm diameter and no longer than 3 metres.[3]Worcester Bosch, Does an external condensate pipe have to be insulated? For other gas or oil boilers, external runs must be kept to a maximum of 3 metres and must be insulated.[3]Worcester Bosch, Does an external condensate pipe have to be insulated? This is installer work, and a boiler repair visit can check the run.
When to call an engineer
If you have thawed the pipe and the EA code returns, or the pipe was not frozen, there is another cause. Do not open the boiler casing. Work on a gas appliance must be done by a Gas Safe registered engineer.[4]Health and Safety Executive, Domestic gas: frequently asked questions If you smell gas at any time, leave the property and call the National Gas Emergency Service on 0800 111 999. This is the number HSE gives for suspected gas leaks.[4]Health and Safety Executive, Domestic gas: frequently asked questions
Example
Ravi in Baildon has a Worcester Bosch combi. After three nights of hard frost the heating does not come on and the boiler makes a gurgling noise. The display shows EA. He finds the white pipe outside, pours warm water from a watering can along it, and resets the boiler. It lights.
Because the pipe froze, he asks his engineer at the next service whether the external run could be shortened or insulated.
What people get wrong
People often see a lockout code and assume the boiler has failed. In freezing weather, Worcester Bosch says the cause can be a frozen condensate pipe, which you can usually thaw yourself. Check the pipe before you ring anyone.
The opposite mistake is using boiling water from a kettle. Worcester says to use warm water and not boiling water.[2]Worcester Bosch, Boiler not working in freezing temperatures?
The bottom line
EA on a Worcester Bosch boiler usually points to a blocked condensate pipe, and in cold weather that often means a frozen one. Worcester says you can usually thaw it safely with warm water and then reset the boiler. If that does not work, or the code keeps returning, book a Gas Safe registered engineer.
Common questions
What does EA mean on a Worcester Bosch boiler?
Worcester Bosch says the boiler may repeatedly lock out or stop working and show an EA code when the condensate pipe is blocked. In freezing weather that is usually because the outdoor pipe has frozen.
How do I fix EA on my Worcester boiler?
If the pipe is frozen and it is safe to reach it, Worcester says to pour warm water, not boiling water, along the outdoor pipe, then reset the boiler. If that does not work, call a Gas Safe registered engineer.
Do all Worcester boilers show EA?
No. Worcester says that, depending on the boiler, a frozen condensate pipe may show as an EA code, a D5 code or a slow flashing blue light. Check your manual for your model.
How can I stop the condensate pipe freezing again?
Worcester suggests turning the boiler's heating control to maximum in freezing weather, fitting a drain cover to protect the pipe end and insulating the external pipework. It also gives limits on external pipe length and size.
Sources
We cite the original source for every figure: government, regulators, standards bodies and manufacturers' own documents. Each one shows the date we last checked it.
- Worcester Bosch. How do I know that my condensate pipe is blocked?. Checked 11 November 2026. ↩
- Worcester Bosch. Boiler not working in freezing temperatures?. Checked 11 November 2026. ↩
- Worcester Bosch. Does an external condensate pipe have to be insulated?. Checked 11 November 2026. ↩
- Health and Safety Executive. Domestic gas: frequently asked questions. Checked 11 November 2026. ↩