BoilerFaultCodesMalvern 300 Fault Code
The Malvern 300 fault code means: your boiler has lost the water pressure it needs to circulate heat around your home and has automatically shut down for safety.. It appears on 1 Malvern model in our database.
Technical description: Pressure Loss
DIY fix possible
Locate the filling loop, which is usually a silver braided hose under the boiler.Slowly open the valves on the filling loop to allow cold mains water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone, ideally around 1.5 bar.Close the valves tightly and check the boiler display to see if the error has cleared.
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Malvern models that show the 300 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Malvern 300 fault code information on this page is sourced and cross-checked against the official Malvern service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026