BoilerFaultCodesIdeal LC4 Fault Code
The Ideal LC4 fault code means: your boiler has detected an internal electrical communication problem with the system that controls the pump and fan, meaning the unit cannot run safely.. It appears on 1 Ideal model in our database.
Technical description: Inverter Error
What causes the Ideal LC4 fault?
This fault occurs when the boiler's main brain loses its connection with the high-voltage component that powers the internal pump and fan. The most common reason is an electronic failure within the inverter board itself or a loose wiring connection preventing these two vital parts from talking to each other. Because the boiler cannot confirm the pump is moving water or the fan is clearing gases, it shuts down as a safety precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the LC4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal LC4 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