BoilerFaultCodesUnical 45 Fault Code
The Unical 45 fault code means: your boiler has switched off because there is too much water pressure in the system, which can cause internal leaks if not corrected.. It appears on 2 Unical models in our database.
Technical description: wATER OVERPRESSURE detected if the H2O pressure Transducer is present with pressure > 2.5 bar; it is reset automatically when H2O pressure < 2 bar
DIY fix possible
Locate a radiator bleed valve and use a key to release water into a container until the boiler pressure gauge drops below 1.5 bar.Ensure the external filling loop valves are tightly closed to prevent more water from entering.Check if the pressure rises again on its own, which may indicate a faulty filling loop or internal valve.
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Unical models that show the 45 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Unical 45 fault code information on this page is sourced and cross-checked against the official Unical service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026