BoilerFaultCodesYour boiler has detected that the water pressure is too low and needs a top-up to continue working safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Pressure needs filling to 0.5 – 0.8 bar
What causes this fault?
This fault occurs when the internal sensors detect that there isn't enough water circulating within the system to operate safely. The most common reason is a slow leak in the pipework or radiators, or air being released through the valves, which naturally reduces the system's pressure over time.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, as stagnant air pockets or minor leaks often manifest during the initial system startup.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath your boiler.Slowly open the valve(s) to allow water into the system while watching the pressure gauge.Close the valves tightly once the pressure reaches between 1.0 and 1.5 bar.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like 1P4 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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