BoilerFaultCodesPotterton Pressure below 0.5 Fault Code
Also written as PRESSUREBELOW05 — same fault.
The Potterton Pressure below 0.5 fault code means: your boiler has stopped working because the water pressure in the system has dropped too low to operate safely.. It appears on 1 Potterton model in our database.
Technical description: If the pressure falls below 0.5, this may indicate a leak on the central heating system.
What causes the Potterton Pressure below 0.5 fault?
This fault occurs when there isn't enough water circulating inside your heating system to safely transfer heat, triggering a safety sensor to shut the boiler down. The most common reasons are a slow leak from a radiator valve or pipework, or the pressure relief valve becoming faulty and letting water escape the system.
This issue is more frequent in autumn when the heating is turned back on after a long break, as changing temperatures can cause seals to weep or highlight existing pressure drops.
DIY fix possible
Locate the silver filling loop underneath the boilerSlowly open both taps/levers on the filling loop until you hear water movingClose both taps tightly once the pressure gauge on the front of the boiler reaches between 1.0 and 1.5 bar
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Potterton models that show the Pressure below 0.5 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Pressure below 0.5 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