High Lockout
9.1.11 on Ideal HP290

Your heat pump's outdoor unit has detected a problem with the sensor that monitors the temperature of the refrigerant gas as it leaves the compressor, causing the system to stop running to prevent damage.

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, Discharge Thermistor (Tp) Error

What causes this fault?

This fault occurs when the control system receives an incorrect or missing signal from the sensor that monitors the heat of the refrigerant gas. It often happens because the sensor has failed internally, or because the electrical wiring connecting it to the main circuit board has become loose or damaged. To prevent the unit from overheating and causing expensive internal damage, the system safely shuts itself down.

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.

Find a Gas Safe engineer
Search the official register →

Related fault codes

9.1.12View →9.1.13View →

Related guides you might find useful

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →