BoilerFaultCodesYour boiler’s water levels have dropped too low for it to start up safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Insufficient system pressure - the system pressure is low
What causes this fault?
This fault occurs when the water pressure inside your central heating system drops below the minimum level required for the boiler to operate. The most common reasons for this are a leak somewhere in the pipework or radiators, or the air pressure in the expansion vessel needing to be topped up by an engineer.
This issue is more frequent in autumn when people turn their heating back on after summer, as the change in temperature can highlight minor leaks or a loss of pressure in the system.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) under the boiler.Slowly open the one or two taps on the loop until you hear water moving.Watch the display until the pressure reaches 1.5 bar, then close the taps tightly.
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 Flashing 0.3 bar — no call-out fees, no surprises.
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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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