BoilerFaultCodesIdeal L3 Fault Code
The Ideal L3 fault code means: your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.. It appears on 1 Ideal model in our database.
Technical description: Low Water Pressure
DIY fix possible
Locate the external filling loop, which is a silver braided hose under the boiler.Open the small black or blue valves on either end of the hose to allow mains water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (usually around 1.5 bar).Close both valves tightly to stop the flow of water.
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Gas Safe Register →Ideal models that show the L3 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal L3 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 27 April 2026