High Lockout
T2B on Ideal HP290

Your heat pump has stopped working because a sensor that monitors the temperature of the internal cooling liquid has detected a problem or failed.

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

Refrigerant Thermistor Error

What causes this fault?

This fault occurs when the system's control board loses communication with the sensor that monitors the temperature of the refrigerant liquid. The most common reason is that the sensor itself has developed an electrical fault or the wiring connecting it to the main controller has become loose or damaged. Because the unit cannot safely monitor these internal temperatures, it shuts down to prevent damage to 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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