BoilerFaultCodes.com
9.1.34 High Lockout

Your heat pump's engine has stopped running because it is struggling to start or has an electrical fault, meaning you have no heating or hot water.

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: Compressor Stall Error and Compressor Start Error and Compressor Terminals Short Circuit (L61) and Compressor Error

What causes this fault?

This fault occurs when the heat pump's compressor, which is the heart of the system, is unable to begin its rotation or suffers an internal electrical short. It is often caused by a mechanical seizure within the unit or a failure in the electronic control board that provides the power to get it moving. Because the compressor cannot pump heat into your home, the system shuts down to prevent further electrical damage.

This fault can be more prevalent during the first cold snap of autumn when the system is required to work at higher pressures after being relatively idle over the summer.

Typical repair cost £600-£1,800 (including labour)

Engineer required

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

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