BoilerFaultCodesYour boiler has shut down because the internal water pressure has become too high, which could potentially cause leaks or damage if not addressed.
Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now — this fault can be dangerous if ignored.
Technical description: Pressure > Pmax error
What causes this fault?
This fault occurs when the water pressure inside your heating system exceeds safe operating limits, triggering an automatic shutdown to protect the internal components. The most common reason is a filling loop valve being left slightly open or failing, which allows fresh water to constantly enter the system, or an internal part called the expansion vessel losing its ability to manage water volume as it heats up.
This issue often surfaces during the first few weeks of winter when the heating is turned on for long periods, causing the water to expand more than it does during the summer months.
DIY fix possible
Check that the filling loop valves are tightly closed.Locate a radiator bleed valve and use a key to release water into a cloth or bowl.Monitor the pressure gauge until it drops back into the green zone (typically 1.0 to 1.5 bar).
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