High Lockout
L43 on Ideal HP290

Your heat pump has stopped working because its internal computer board is having trouble communicating with the compressor system.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 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 main control board loses its digital connection with the inverter, which is the component responsible for managing the heat pump's power. The most common reason is an internal electronic component failure or a loose connection in the wiring that prevents the system from safely starting the compressor.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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