BoilerFaultCodesIdeal F0U Fault Code
The Ideal F0U fault code means: your boiler has shut down because it is getting too hot too quickly, usually because the water isn't flowing through the system as it should.. It appears on 1 Ideal model in our database.
Technical description: Flow/Return Differential Greater than 50°C
DIY fix possible
Check that all radiator valves (TRVs) are fully open to allow water to circulate.Ensure your boiler pressure is between 1.0 and 1.5 bar on the gauge.Reset the boiler using the control knob or reset button.
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Ideal models that show the F0U fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal F0U fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026