BoilerFaultCodesTechnical description
Filling test program. The diverter valve moves to the centre position
What causes this fault?
This is a routine diagnostic phase where the boiler verifies there is enough water pressure to operate safely. It occurs when the appliance is first powered on or after a periods of inactivity, as the system checks that the internal valves are in the correct position. It is a sign the boiler is performing its internal safety checks rather than an indication that a part has failed.
DIY fix possible
Wait approximately 15 minutes for the program to finishEnsure your external or internal filling loop is closedCheck that the pressure gauge is between 1.0 and 1.5 bar
Find a Gas Safe engineer
Search the official register →