BoilerFaultCodesPotterton E119 Fault Code
The Potterton E119 fault code means: your boiler has stopped working because the water pressure is too low for the system to run safely.. It appears on 10 Potterton models in our database.
Technical description: Water Pressure Switch Not Operated / primary water pressure is less than 0.5 bar
What causes the Potterton E119 fault?
This fault occurs when the pressure of the water circulating inside your heating system drops below a safe working level, usually because of a small leak or after you have recently bled your radiators. Without enough water pressure, the boiler cannot safely move heat around your home, so it shuts down to prevent the internal components from overheating. While often fixed by topping up the system, persistent pressure loss may indicate a failing part like the expansion vessel.
This code is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, as natural pressure loss often occurs during periods of inactivity.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) under or near the boiler.Slowly open the one or two taps/levers on the filling loop until you hear water entering.Watch the pressure gauge and close the taps once the needle reaches between 1.0 and 1.5 bar.
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Gas Safe Register →Potterton models that show the E119 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton E119 fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026