BoilerFaultCodes.com
L65 High Lockout

Your heat pump has stopped working because of a communication or electrical issue within its internal power control unit.

Call an engineer soon

Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Inverter Error

What causes this 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.

Typical repair cost £450-£950 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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