BoilerFaultCodesIdeal 9.1.10 Fault Code
Also written as 9110 — same fault.
The Ideal 9.1.10 fault code means: your heat pump's outdoor unit has detected a problem with a temperature sensor that monitors the cooling fluid, preventing the system from heating your home efficiently.. It appears on 1 Ideal model in our database.
Technical description: Outdoor Unit, Compressor Refrigerant Return Thermistor (Th) Error
What causes the Ideal 9.1.10 fault?
This fault occurs when the control system receives an illogical or missing temperature reading from the sensor monitoring the liquid returning to the compressor. It is usually caused by the sensor itself failing internally or a break in the electrical wiring connecting the sensor to the main control board. Without this data, the unit shuts down to prevent potential damage to the refrigeration cycle.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the 9.1.10 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 9.1.10 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