BoilerFaultCodesIntergas F003 Fault Code
The Intergas F003 fault code means: your boiler has detected that the exhaust gases are getting too hot, so it has shut down as a safety precaution to prevent internal damage.. It appears on 4 Intergas models in our database.
Technical description: Flue gas temperature is too high.
What causes the Intergas F003 fault?
This fault occurs when the internal heat exchanger cannot transfer heat into the water efficiently, causing the waste gases to reach a dangerous temperature. The most common reason is a buildup of limescale or debris inside the heat exchanger, but it can also be caused by a faulty sensor or a damaged burner seal allowing heat to escape where it shouldn't.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Intergas models that show the F003 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Intergas F003 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 7 July 2026