BoilerFaultCodesWorcester Bosch E00-711 Fault Code
Also written as E00711 — same fault.
The Worcester Bosch E00-711 fault code means: your boiler is struggling to transfer heat to your hot water because a key internal component is likely blocked or damaged.. It appears on 1 Worcester Bosch model in our database.
Technical description: Water to Water Heat Exchanger Giannoni, Ref. PVW 14 E
What causes the Worcester Bosch E00-711 fault?
This fault occurs when the boiler's internal sensors detect that heat isn't being transferred effectively to your taps, usually due to a buildup of limescale or heating sludge inside the secondary heat exchanger. The most common reason is 'sludging' from the main heating circuit, which creates a physical blockage that prevents the cold water from heating up properly. In some cases, a failing diverter valve may also be preventing the hot water from flowing into the correct part of the system.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Worcester Bosch models that show the E00-711 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch E00-711 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