Error EA 229 or D5

Safety precautions:

- If you smell gas or suspect a gas leak, leave the property immediately and call the gas emergency number. Do not operate electrical switches or the boiler.

- Turn the boiler off at the programmer and isolate electrical supply at the fused spur or consumer unit before opening the boiler casing. Only perform internal checks if you are competent; otherwise leave internal inspection to a Gas Safe engineer.

- Use care with ladders and working at height, and avoid water contacting electrical sockets or components.

- Do not use naked flames, blow torches or high-temperature heat guns on the pipework. Do not pour boiling water directly onto plastic pipework (use warm water) and avoid scald risk.

Initial checks a homeowner can do:

- Confirm the error display: EA 229 or D5 and note any flashing lights or symptoms (boiler locks out, immediate shutdown, gurgling noises when starting).

- Locate the condensate pipe: it is usually a small white plastic pipe (around 21.5 mm) that runs from under the boiler to the outside of the building. Follow it to the external discharge point.

- Visually inspect the external run for frost/ice, blockages, leaves, drain covers or bird nests. Check the small flexible section directly under the boiler for kinks or detachment.

- Listen for gurgling or water noises inside the boiler when it attempts to start — that indicates drainage problems.

Diagnostic and fix steps:

1) Turn off the boiler at the programmer and isolate the electrical supply to the boiler (switch at the fused spur or consumer unit). Allow a short cool-down period.

2) Locate the frozen section of condensate pipe. If the external pipe or the trap shows visible ice or frost, it is likely frozen.

3) Thaw the pipe safely: slowly pour warm (not boiling) water over the frozen section, or apply a hot water bottle wrapped in a towel. A hairdryer on a medium/low setting can be used if power/extension leads are safe and dry. Repeat as needed until water begins to flow. Do not use an open flame or heat gun.

4) Clear any visible external debris or remove an external drain cap or strainer if fitted and clear blockages. If condensate discharges into a shared gully or soil stack, check for external blockages and clear them if safe to do so.

5) Check the internal condensate trap/sump if your manual shows it is user-accessible: some boilers have a small condensate trap or removable pipe section under the unit. If it is safe and the manual allows, you can carefully remove and clear it of ice or sludgy deposits, then refit. If you are not sure, leave this to an engineer.

6) Secure and straighten any kinked flexible condensate tubing under the boiler. Make sure pipework slopes downhill from the boiler to the outside exit.

7) Once you believe the condensate flow is restored, restore electrical power to the boiler and reset it using the reset button (usually hold the reset for around 10 seconds; check the boiler manual for model-specific instructions). Observe the boiler through a start cycle to ensure it ignites and runs without locking out.

8) If the boiler starts and runs normally, leave it running and listen for gurgling or reappearance of the fault. If the fault returns or you still get EA 229/D5, there may be an internal problem or another cause.

Prevention and longer-term fixes:

- Insulate/lag the external condensate run with suitable pipe insulation to reduce the chance of refreezing.

- Consider rerouting the condensate pipe to an internal waste, increasing the pipe diameter, or fitting a trace heating cable or frost heater if freezing is frequent. These measures should be discussed and fitted by an installer or Gas Safe engineer.

- Fit a drain cover or guard to stop leaves, debris and vermin entering the discharge.

When to call a professional:

- If thawing and clearing the external pipe does not clear the fault or the error returns repeatedly.

- If you are not confident to isolate power, access internal traps, or use tools around the boiler.

- If you suspect gas supply problems (including frozen meter regulator), flue blockage, persistent flame instability, PCB or gas valve faults, or if the gas valve or burner requires cleaning or adjustment. These are gas-related repairs that must be carried out by a Gas Safe registered engineer.

- If you detect any signs of water ingress to the boiler electronics, unusual smells, or other worrying symptoms.

If in doubt, stop and call a Gas Safe registered engineer or Worcester Bosch support for advice. Do not attempt internal gas or electrical repairs yourself.