High Lockout
J43 on Ideal HP290

Your heat pump's internal control board has detected a communication or electrical fault with the motor that drives the system, meaning it cannot currently provide heating.

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 the ability to communicate with or power the motor that drives the heat pump. It is usually caused by a failure in the electrical components that manage the compressor's speed, or a physical electrical fault within the compressor itself. When this happens, the system cannot safely move heat into your home and will shut down to prevent further damage.

This fault is more frequent during extreme cold spells when the system is working at its maximum capacity to maintain indoor temperatures.

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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