BoilerFaultCodesWorcester Bosch D4 341 Fault Code
Also written as D4341 — same fault.
The Worcester Bosch D4 341 fault code means: your boiler is shutting down because the water inside is heating up much faster than the system can move it around, which usually points to a blockage or a pump issue.. It appears on 2 Worcester Bosch models in our database.
Technical description: Primary flow temperatures rising too fast
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Worcester Bosch models that show the D4 341 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch D4 341 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 7 July 2026