BoilerFaultCodesIdeal Low system pressure Fault Code
Also written as LOWSYSTEMPRESSURE — same fault.
The Ideal Low system pressure fault code means: your boiler has stopped working because the water level inside the system has dropped too low and needs topping up.. It appears on 1 Ideal model in our database.
Technical description: Pressure reading below 0.5 bar on the gauge
What causes the Ideal Low system pressure fault?
This fault occurs when the internal water pressure drops below the minimum level required for the boiler to operate safely. The most common reason is a slow leak from a radiator valve or a pipe joint, but it can also happen if you have recently bled your radiators and didn't top up the system afterwards. In some cases, a component inside the boiler like the pressure relief valve may be letting water out of the system gradually.
This fault is frequently seen at the start of autumn when homeowners turn their heating back on for the first time after the summer break.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Slowly open the one or two small tap handles until you hear water running.Watch the pressure gauge and close the taps firmly once it reaches between 1 and 1.5 bar.
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Gas Safe Register →Ideal models that show the Low system pressure fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal Low system pressure 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