BoilerFaultCodesIdeal LED 4 lit Fault Code
Also written as LED4LIT — same fault.
The Ideal LED 4 lit fault code means: your boiler is receiving power correctly, but it has failed to ignite or stay lit, causing it to shut down for safety.. It appears on 1 Ideal model in our database.
Technical description: Indicates that the fuse on PCB 37 is OK.
What causes the Ideal LED 4 lit fault?
This fault occurs when the boiler's control system attempts to start the heating process but cannot detect a stable flame. The most common reasons are a worn-out component that creates the spark, a failure in the valve that delivers gas to the burner, or a fault within the main control board that manages the ignition sequence.
DIY fix possible
Check that your gas supply is turned on at the meterPress the reset button on the front control panelMonitor the boiler to see if it fires up or if the light returns
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Gas Safe Register →Ideal models that show the LED 4 lit fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal LED 4 lit 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