BoilerFaultCodesIntergas F04 Fault Code
The Intergas F04 fault code means: your boiler has stopped working because it cannot detect a signal from the internal sensor that monitors the temperature of your hot water.. It appears on 3 Intergas models in our database.
Technical description: S2 sensor open circuit
What causes the Intergas F04 fault?
This fault occurs when the boiler's control board loses communication with the sensor responsible for monitoring your hot water temperature. The most common cause is the sensor itself failing internally, but it can also be triggered by a loose connection or damaged wiring between the sensor and the main circuit board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Intergas models that show the F04 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Intergas F04 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