BoilerFaultCodesIdeal LC9 Fault Code
The Ideal LC9 fault code means: your heat pump’s internal power electronics have become too hot and have shut the system down to prevent damage.. It appears on 1 Ideal model in our database.
Technical description: Inverter High Temperature
What causes the Ideal LC9 fault?
This fault occurs when the power electronics that drive the heat pump compressor reach a safety temperature limit. It is usually caused by a failure of the internal cooling fan or a build-up of dust and debris blocking the heatsink, preventing the system from shedding heat effectively. When the electronics cannot stay cool, the unit shuts down to prevent permanent component failure.
This fault is more common during summer heatwaves, as high ambient temperatures make it harder for the unit's internal cooling system to keep the electronics within safe limits.
DIY fix possible
Check that the outdoor unit is not covered or its air vents blocked by leaves or debris.Ensure there is at least a one-metre clear space around the outdoor unit for proper airflow.Turn the power to the unit off at the isolator switch, wait 5 minutes, and turn it back on to see if the code clears once cooled.
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Gas Safe Register →Ideal models that show the LC9 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal LC9 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