9.1.28 High

Ideal 9.1.28 Fault Code

Also written as 9128 — same fault.

The Ideal 9.1.28 fault code means: your heat pump has stopped working because a sensor detected that the internal system is getting too hot, likely due to a lack of proper airflow or low refrigerant levels.. It appears on 1 Ideal model in our database.

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: Compressor Discharge Temperature High Error

What causes the Ideal 9.1.28 fault?

This fault occurs when the temperature of the gas leaving the compressor becomes dangerously high, causing the system to shut down to prevent internal damage. It is usually caused by the system struggling to move heat away efficiently, often due to a leak in the refrigerant gas or a mechanical part failing to regulate the flow correctly.

This issue is more frequent during summer heatwaves, as the high outdoor temperature makes it much harder for the unit to keep its internal components cool while operating.

Typical repair cost £150-450 (including labour)

Engineer required

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

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Ideal models that show the 9.1.28 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ideal 9.1.28 fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026