EF 349 Medium

Worcester Bosch EF 349 Fault Code

Also written as EF349 — same fault.

The Worcester Bosch EF 349 fault code means: your boiler is working harder than it should because water isn't circulating properly through the system, causing the pipes leading out of the boiler to be much hotter than those coming back.. It appears on 11 Worcester Bosch models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Central heating boil detected – boiler operating at minimum burner load with temperature difference greater than 18°C between Flow & Return.
Typical repair cost £120-280 (including labour)

DIY fix possible

Check that all radiator valves are fully openBleed all radiators to remove trapped airEnsure the system pressure is between 1.0 and 1.5 bar

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Worcester Bosch models that show the EF 349 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch EF 349 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026