BoilerFaultCodesPotterton 119 Fault Code
The Potterton 119 fault code means: your boiler has stopped working because the water pressure in the central heating system has dropped too low.. It appears on 1 Potterton model in our database.
Technical description: CH system pressure less than 0.5 bar / water pressure switch fault
What causes the Potterton 119 fault?
This fault occurs when the internal sensor detects that the water pressure has dropped below the minimum level required for the boiler to operate safely. The most common reason is a slow leak somewhere in your radiators or pipework, or simply that the expansion vessel needs recharging. Without enough water pressure, the boiler cannot circulate heat effectively and will shut down to prevent internal damage.
This fault is frequently seen in autumn when the heating is turned on for the first time after summer, as air can trapped in radiators and settled leaks become apparent.
DIY fix possible
Locate the internal or external filling loop (flexible silver hose) under the boiler.Slowly open the valve(s) to allow water into the system while watching the pressure gauge.Close the valves firmly once the needle reaches between 1.0 and 1.5 bar.
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Gas Safe Register →Potterton models that show the 119 fault code
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Source
Potterton 119 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