BoilerFaultCodesYour boiler has detected that there is not enough water pressure in the system to operate safely, causing it to shut down.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Primary system water pressure too low
What causes this fault?
This fault occurs when the water level inside your heating system drops below the minimum required amount, making it unsafe for the boiler to fire up. The most common reasons for this drop are a small leak in the pipework or radiators, or the need to bleed air from the system after a period of inactivity. If the pressure continues to drop after you refill it, a component inside the boiler like the expansion vessel may be failing.
This code is frequently seen in autumn when homeowners turn their heating back on for the first time, as small leaks or trapped air can cause the pressure to dip during the summer months.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Slowly open the one or two taps on the filling loop until you hear water flowing.Monitor the pressure gauge and close the taps when the needle reaches between 1 and 1.5 bar.
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A boiler cover plan would cover faults like E118 — 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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