How much does it cost to fix Worcester Bosch error code D4 341?

Typical repair cost for the Worcester Bosch D4 341 fault is £120-350 including labour.

D4 341 High

Worcester Bosch D4 341 Fault Code

Q: What does the Worcester Bosch D4 341 fault code mean?

Your boiler is heating up much quicker than it should and is shutting down to prevent overheating, likely because the water isn't moving through the system properly.

Also written as D4341 — same fault.

The Worcester Bosch D4 341 fault code means: your boiler is heating up much quicker than it should and is shutting down to prevent overheating, likely because the water isn't moving through the system properly.. It appears on 12 Worcester Bosch models in our database.

Technical description: Primary flow temperature rising too fast

Typical repair cost £120-350 (including labour)

DIY fix possible

Check that all radiator valves are fully openEnsure the system pressure is between 1 and 1.5 bar on the pressure gaugeCheck if the pump is running by listening for a gentle humming sound

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

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 27 April 2026