BoilerFaultCodesYour boiler is unable to detect the necessary internal water pressure increase required to start the heating process.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Pump run/pressure sensor fault
What causes this fault?
This fault occurs when the boiler's internal computer fails to detect a small surge in water pressure that should happen the moment the pump starts spinning. The most common reason is that the pressure sensor has become blocked with sludge or the pump itself has seized, meaning the system cannot confirm it is safe to ignite.
This issue is more frequent in autumn when the heating is turned on for the first time after summer, as pumps often seize during long periods of inactivity.
DIY fix possible
Check the pressure gauge and ensure it is between 1.0 and 1.5 barIf the pressure is low, use the filling loop to top up the system waterReset the boiler to see if the fault clears
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A boiler cover plan would cover faults like F.75 — no call-out fees, no surprises.
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