System pressure has dropped too low for the boiler to run, so it has stopped and shown F1.
Most common on: Logic, Logic+, Vogue
F1 means the water pressure in the sealed heating system has fallen below the minimum the boiler needs, typically around 0.5 bar. The boiler stops firing until the pressure is brought back up.
Low pressure is one of the few faults a homeowner can usually put right. Topping up via the filling loop often clears it — but pressure that keeps dropping points to a leak or a failed expansion vessel that needs an engineer.
Check the built-in pressure display or gauge. If it reads below about 1 bar, the system needs topping up.
Open the filling loop slowly until the gauge reads about 1.0–1.5 bar (cold), then close both ends of the loop.
Once pressure is restored, press reset. The F1 should clear and the boiler should run again.
If the pressure keeps falling, there is a leak or an expansion vessel fault — book a Gas Safe engineer rather than topping up repeatedly.
Work on the gas side of a boiler must be carried out by a Gas Safe registered engineer. The checks above are limited to safe, non-invasive things a homeowner can look at (pressure, resets, the gas supply) — if in doubt, stop and call an engineer.
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System pressure has dropped too low for the boiler to run, so it has stopped and shown F1. F1 means the water pressure in the sealed heating system has fallen below the minimum the boiler needs, typically around 0.5 bar. The boiler stops firing until the pressure is brought back up.
Often yes — this one is frequently resolved by a homeowner. Check the built-in pressure display or gauge. If it reads below about 1 bar, the system needs topping up. If it keeps coming back, book a Gas Safe registered engineer.
A recurring F1 means the underlying cause has not been fixed — most often gradual pressure loss over time (normal — needs occasional topping up). Resetting repeatedly will not solve it; get the boiler diagnosed properly.