BoilerFaultCodesYour boiler has lost water pressure or isn't circulating water correctly, causing it to shut down for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Heating circuit pressure low (less than 1 bar), pump failure, or water flow detector / microswitch fault
What causes this fault?
This fault occurs when there isn't enough water pressure in the system to operate safely, or the internal pump is failing to move the water around. The most common reason is a slow leak from a radiator valve or a lost charge in the expansion vessel, leading to a drop in pressure. In some cases, the internal sensor that detects water flow has simply become stuck or faulty.
This fault often appears in autumn when the heating is turned on for the first time after summer, as stagnant pumps can seize or pressure may have dropped while the system was idle.
DIY fix possible
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.Locate the filling loop (braided flexible hose) underneath the boiler.Slowly open the valves until the pressure reaches 1.5 bar, then ensure they are closed tightly.Press the reset button to restart the boiler.
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