BoilerFaultCodesIntergas F012 Fault Code
The Intergas F012 fault code means: your boiler has stopped working because its internal temperature sensor is reporting an error, meaning it can no longer monitor heat levels safely.. It appears on 4 Intergas models in our database.
Technical description: Flue gas sensor S5 fault.
What causes the Intergas F012 fault?
This fault occurs when the boiler's internal S5 temperature sensor stops sending a reliable signal to the main control board. It is usually caused by the sensor's electrical resistance falling outside of its normal range due to internal component failure or a loose connection in the wiring harness. Because the boiler can no longer accurately monitor heat levels, it 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.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like F012: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Intergas models that show the F012 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Intergas F012 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