High Lockout
9.1.9 on Ideal HP290

Your heat pump has stopped working because water is not moving through the outdoor unit properly.

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

Outdoor Unit, No Water Flow, Error

What causes this fault?

This fault occurs when the system detects that water isn't moving through the outdoor unit at the required speed to safely exchange heat. The most common reasons are a build-up of debris or sludge blocking the internal filter, a failure of the main circulation pump, or trapped air pockets within the pipework. When the water stops moving, the unit shuts down to prevent the refrigerant system from overheating or freezing.

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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Related fault codes

9.1.8View →

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