How much does it cost to fix Worcester Bosch error code H1?

Typical repair cost for the Worcester Bosch H1 fault is £150-300 including labour.

H1 High

Worcester Bosch H1 Fault Code

Q: What does the Worcester Bosch H1 fault code mean?

Your boiler has detected that the internal water storage tank is becoming dangerously hot, so it has safely shut itself down to prevent damage.

The Worcester Bosch H1 fault code means: your boiler has detected that the internal water storage tank is becoming dangerously hot, so it has safely shut itself down to prevent damage.. It appears on 5 Worcester Bosch models in our database.

Technical description: Tank overheat

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 H1 fault code

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

Greenstar Utility 18/25 Repair: £100-300
Highflow 250 Repair: £150-300
Highflow 300 Repair: £150-300
Highflow 440 CDi Repair: £150-300
Highflow 550 CDi Repair: £150-300

Source

Worcester Bosch H1 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