BoilerFaultCodesYour boiler has too much water inside it, causing the internal pressure to rise to an unsafe level.
Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now — this fault can be dangerous if ignored.
Technical description: System pressure high (> 2.8 bar)
What causes this fault?
This fault occurs when the water pressure inside your system exceeds a safe working limit, usually because too much water has been added via the filling loop. It can also happen if the internal parts that manage pressure, such as the expansion vessel, have failed or if a valve is leaking water into the system constantly.
This fault is often seen after homeowners bleed their radiators in autumn or winter and accidentally leave the filling valves open or overfill the system.
DIY fix possible
Check that the silver filling loop valves are tightly closedSwitch off the boiler and wait for it to coolBleed water from a radiator using a bleed key until the pressure gauge drops to 1.5 barRestart the boiler
Find a Gas Safe engineer
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Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E18 — 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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