BoilerFaultCodesWorcester Bosch H07 Fault Code
The Worcester Bosch H07 fault code means: your boiler has detected that the water pressure in the system is too low, causing it to reduce its output or stop working to prevent damage.. It appears on 10 Worcester Bosch models in our database.
Technical description: The current water pressure is too low, limiting the performance in heat mode as well as domestic hot water (DHW) mode
What causes the Worcester Bosch H07 fault?
This fault occurs when the system loses the physical water pressure required to circulate heat effectively through your radiators. The most common reasons are a slow leak hidden somewhere in your pipework or the pressure naturally dropping after you have recently bled your radiators.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, revealing pressure losses that occurred while the system was idle.
DIY fix possible
Locate the external filling loop, which is usually a silver flexible hose beneath or near the boiler.Open the one or two taps on the filling loop slowly until you hear water entering the system.Monitor the pressure gauge on the boiler front or digital display and close the taps once it reaches 1.5 bar.
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Gas Safe Register →Worcester Bosch models that show the H07 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch H07 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