Error E9 224

Safety first: do not open the boiler casing or attempt gas/electrical repairs. If you smell gas, evacuate and call the gas emergency number immediately. Turn off the boiler and isolate electrical supply if you are going to work on external pipework; however some diagnostic checks require the boiler powered on (see steps below). Only perform the basic external checks described here — anything internal must be done by a qualified engineer.

Initial homeowner checks (safe, simple):

1) Note the exact error (E9 224) and any other cause codes shown. Take a photo of the display and the boiler model/serial for the engineer.

2) Try a single reset: allow the boiler to cool for 10–20 minutes, then press the reset button according to the manual. If the fault clears and does not return, monitor the boiler closely over the next heating cycle. If it returns, stop and call a Gas Safe engineer.

3) Check the external condensate pipe (typically a small plastic pipe that runs to a drain or outside). In cold weather it commonly freezes. If you see frost or ice, carefully thaw with warm (not boiling) water or a warm cloth until water flows freely. Do not use a blowtorch or boiling water. After thawing, run the boiler and see if the fault clears.

4) Check system pressure on the boiler gauge when cold — ideal is around 1–1.5 bar. If pressure is very high (above about 2.5 bar) that can cause safety trips; if it is too high you can reduce pressure by bleeding a radiator (use a radiator key, catch water in a cloth/ bowl, close the valve when water appears). Recheck the gauge. If pressure is persistently too high or you are unsure, stop and call an engineer.

5) Listen for the central heating pump when the system calls for heat (radiators requested). You should hear or feel the pump running and pipes should warm after a short while. If the pump is silent, noisy, or pipes stay cold, this indicates a circulation fault that often causes overheating and E9. Do not try to dismantle the pump yourself.

Further diagnostic steps to report to an engineer (do not attempt internal repairs):

6) If you can safely observe operation while the boiler is powered, note whether the fan runs on ignition attempt and whether there are unusual noises or visible leaks. Record what you see/ hear so the engineer has full information.

7) Do not repeatedly reset the boiler. One attempt after cooling is reasonable; repeated resets can mask progressive faults and are not a substitute for a proper diagnosis.

8) If condensate was clear and pressure and pump checks show issues (pump not running, noise, or poor circulation), or if the fault persists after thawing and one reset, arrange a Gas Safe registered Worcester Bosch‑competent engineer. The likely professional tasks include verifying the safety sensor and wiring continuity, testing/ replacing the high‑limit thermostat or safety temperature sensor, checking and servicing the pump, inspecting the heat exchanger for scale or blockages, checking the fan and PCB operation, and fixing any stuck PRV or internal blockage.

What to tell the engineer and next steps:

9) Provide the exact error code (E9 224), when it first appeared, the results of your condensate and pressure checks, whether a reset cleared the fault temporarily, any noises you noticed, and photos you took. This helps speed diagnosis.

10) Do not attempt to work on gas or electrical components yourself. Arrange a Gas Safe registered engineer if the fault persists or if you are not confident with any of the checks above. The engineer can safely inspect sensors, wiring, pump, heat exchanger and replace parts as required.

Summary: You can safely try one reset, check and thaw the external condensate pipe if frozen, check system pressure and bleed a radiator to reduce excess pressure, and listen for the pump. If the fault remains or you find pump/circulation problems, sensor wiring issues, high pressure that won’t reduce, or repeated lockouts, call a Gas Safe qualified engineer to diagnose and repair. Do not open the boiler or attempt gas/electrical repairs yourself.