BoilerFaultCodesIdeal 9.1.29 Fault Code
Also written as 9129 — same fault.
The Ideal 9.1.29 fault code means: your heat pump has stopped working because it cannot accurately monitor the water pressure in the system.. It appears on 1 Ideal model in our database.
Technical description: Low Pressure Sensor Error
What causes the Ideal 9.1.29 fault?
This fault occurs when the heat pump's control board loses communication with the sensor that monitors water pressure within the system. The most common reason is an electrical failure within the sensor itself or a loose connection in the wiring harness. Because the unit cannot verify if there is enough water to operate safely, it shuts down to prevent internal damage.
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 9.1.29 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal 9.1.29 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