BoilerFaultCodesYour boiler has stopped working because the water pressure in the system is too low.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: System pressure falls below 0.5 bar (Control display will warn/Burner control goes to safety shut-down)
What causes this fault?
This fault occurs when there is not enough water inside your heating system to safely allow the boiler to fire up. 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 the pressure back up.
This code is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, revealing pressure drops that occurred while the system was idle.
DIY fix possible
Locate the filling loop (usually two braided hoses or internal levers under the boiler)Slowly open both taps/valves to allow water into the systemClose the valves tightly once the pressure gauge on the display 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 →Protect yourself from future repair bills
A boiler cover plan would cover faults like p < 0.5 — no call-out fees, no surprises.
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Potterton Powermax HE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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