BoilerFaultCodesIdeal L65 Fault Code
The Ideal L65 fault code means: your heat pump has stopped working because of a communication or electrical issue within its internal power control unit.. It appears on 1 Ideal model in our database.
Technical description: Inverter Error
What causes the Ideal L65 fault?
This fault occurs when the heat pump's internal power brain, known as the inverter, fails to communicate with the rest of the system or cannot manage the electricity needed to run the compressor. It is usually caused by an electrical failure within the inverter circuit board or loose wiring connections that disrupt the flow of data. Essentially, the component responsible for regulating the unit's speed and power has suffered a technical glitch or a hardware breakdown.
This error can be more prevalent during summer or extreme heatwaves, as the inverter components are under higher thermal stress while trying to keep the system cool.
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 L65 fault code
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Source
Ideal L65 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