BoilerFaultCodesWorcester Bosch I Fault Code
The Worcester Bosch I fault code indicates a fault on your boiler. It appears on 2 Worcester Bosch models in our database.
Technical description: Water temperature too cool: Low gas pressure, Pot P1 not turned up, Stiff/sticking gas valve, Stiff/sticking flow sensor, Board fault.
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 I fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch I 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 31 August 2026