Error 226

Safety first

- Do not work inside the boiler or remove internal covers unless you are a Gas Safe registered engineer. Boilers contain live electrical parts, gas connections and hot surfaces. Incorrect actions can cause gas leaks, electric shock or void warranties.

- If you smell gas, leave the property immediately and call the gas emergency service. Do not operate electrical switches, appliances or the boiler.

- Turn the boiler off at the external mains switch and at the boiler’s on/off control if you feel unsure, but only isolate power if you are not attempting an immediate reset.

Initial checks a homeowner can do

1. Look at the boiler display and note the code exactly (226) and any flashing cause codes or symbols. Take a photo of the display for reference.

2. Check the exterior of the boiler for any attached leads, cables or external diagnostic devices that could be a service tool. Typical locations are under the front panel, around the underside of the casing or near the control PCB. Do not remove covers to look for internal connections.

3. Check basic operating conditions: ensure the boiler has power, the heating/CH programmer/thermostat is calling for heat, and system water pressure is around 1.0–1.5 bar when cold (only view the pressure gauge; do not open valves unless you know how).

Basic diagnostic and fix steps (safe, homeowner-level)

1. If you see an external plug or cable clearly attached that looks like a diagnostic lead and you can remove it safely without opening the boiler, gently unplug it and then perform a reset (see step 3). If you are unsure whether a lead is safe to remove, do not pull it — call an engineer.

2. Try a simple reset: press the boiler’s Reset button once. If no dedicated Reset button, switch the boiler off at the mains for 30 seconds and switch back on. After reset, watch the display for the code to clear and for the boiler to attempt to run.

3. If the code clears and the boiler runs normally, monitor it for a short period to confirm normal operation. Note the circumstances when the error appeared so you can mention them at your next service.

4. If the code 226 returns immediately or the boiler will not reset, switch the boiler off and record the display, any lights or flashing symbols, and the gas line and water pressure status. Do not attempt to open the boiler casing.

If there is no obvious external service tool attached

- The error can indicate a software/board issue or that a previous engineer left a tool attached internally. In this situation you should contact a Worcester Bosch accredited engineer or a Gas Safe registered heating engineer to inspect the control connections and clear the blocking history safely.

- When contacting an engineer, tell them you have error 226 (service tool connected in blocking error history menu), what you tried (reset/power-cycle), and provide photos of the display and the boiler serial number if possible.

When to call a professional

- Call a Gas Safe registered engineer if the reset does not clear the error, if you cannot identify or safely remove an external diagnostic lead, if you smell gas, or if you suspect internal faults (control board, wiring or persistent lockouts). Only a qualified engineer should open the boiler, inspect internal connectors, clear service-tool flags in the menu, or replace control components.

Additional tips

- Before the engineer arrives, note the boiler model and serial number and the exact sequence of events (e.g., power cut, service visit, cold weather) that preceded the error. This helps diagnosis.

- Do not attempt internal electrical or gas repairs yourself. Clearing the code by unplugging internal connectors or replacing electronics without qualification can be dangerous and may invalidate warranties.

If you want, provide a photo of the boiler display and the area under the front panel (without removing covers) and I can help interpret what you are seeing and advise whether it looks like an externally removable service connection or if you should call an engineer.