BoilerFaultCodesIntergas F03 Fault Code
The Intergas F03 fault code means: your boiler has stopped working because its internal temperature sensor cannot send information to the main control board.. It appears on 3 Intergas models in our database.
Technical description: S1 sensor open circuit
What causes the Intergas F03 fault?
This fault occurs when the boiler's main control board loses its electrical connection with the primary temperature sensor. This is usually caused by the internal sensor failing completely or a loose connection in the wiring harness that prevents data from being transmitted. Without this temperature reading, the boiler shuts down as a safety precaution to prevent overheating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Intergas models that show the F03 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Intergas F03 fault code information on this page is sourced and cross-checked against the official Intergas service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026