How much does it cost to fix Worcester Bosch error code 374 8C?

Typical repair cost for the Worcester Bosch 374 8C fault is £150-300 including labour.

374 8C High

Worcester Bosch 374 8C Fault Code

Q: What does the Worcester Bosch 374 8C fault code mean?

Your boiler has detected repeated issues with maintaining its flame during operation, so it has locked itself for safety to ensure it does not attempt to fire incorrectly.

Also written as 3748C — same fault.

The Worcester Bosch 374 8C fault code means: your boiler has detected repeated issues with maintaining its flame during operation, so it has locked itself for safety to ensure it does not attempt to fire incorrectly.. It appears on 2 Worcester Bosch models in our database.

Technical description: Super-Lock caused by too frequent ionisation loss during burning

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 374 8C fault code

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

Source

Worcester Bosch 374 8C 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