BoilerFaultCodesIdeal L 1 Fault Code
Also written as L1 — same fault.
The Ideal L 1 fault code means: your boiler has stopped working because it has either detected that it is getting too hot or there is not enough water moving through the system.. It appears on 1 Ideal model in our database.
Technical description: Flow Temperature Overheat or No Water Flow
DIY fix possible
Check the pressure gauge on the front of the boiler is between 1 and 1.5 barOpen all radiator valves to ensure water can flow freelySwitch the boiler off and back on at the mains to reset the system
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Ideal models that show the L 1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal L 1 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