How much does it cost to fix Worcester Bosch error code 342 D4?

Typical repair cost for the Worcester Bosch 342 D4 fault is £150-300 including labour.

342 D4 High

Worcester Bosch 342 D4 Fault Code

Q: What does the Worcester Bosch 342 D4 fault code mean?

Your boiler has detected that the water inside is heating up much faster than it is supposed to, which often means there is not enough water flowing through the system to carry the heat away properly.

Also written as 342D4 — same fault.

The Worcester Bosch 342 D4 fault code means: your boiler has detected that the water inside is heating up much faster than it is supposed to, which often means there is not enough water flowing through the system to carry the heat away properly.. It appears on 2 Worcester Bosch models in our database.

Technical description: HW: supply temperature rising too fast

Typical repair cost £150-300 (including labour)

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 342 D4 fault code

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

Source

Worcester Bosch 342 D4 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