BoilerFaultCodesPro F1 Fault Code
The Pro F1 fault code means: your boiler has detected that there is not enough water in the system to operate safely, which is usually caused by a small leak or air being bled from a radiator.. It appears on 1 Pro model in our database.
Technical description: LOW WATER PRESSURE
DIY fix possible
Locate the filling loop (a flexible silver hose) underneath the boiler.Slowly open the one or two taps on the loop until you hear water flowing.Watch the pressure gauge until it reaches 1.5 bar, then turn the taps off tightly.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like F1: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Pro models that show the F1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Pro F1 fault code information on this page is sourced and cross-checked against the official Pro service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026