H03 Low

Worcester Bosch H03 Fault Code

The Worcester Bosch H03 fault code means: your boiler is simply reminding you that it is time for its annual safety service to ensure it continues running efficiently and safely.. It appears on 3 Worcester Bosch models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: The number of operating hours set for service interval has expired.
Typical repair cost £90-140 (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 H03 fault code

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

Source

Worcester Bosch H03 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