BoilerFaultCodesTechnical description
High system pressure – the boiler needs to discharge water down to 0.8 bar
What causes this fault?
This fault occurs when the water pressure inside your heating system rises above the safe operating limit, causing the boiler to shut down for safety. The most common reasons are that the filling loop was left slightly open after topping up the system, or an internal component like the expansion vessel has failed and can no longer manage the pressure changes.
This fault is more frequent when you first turn the heating on after summer, as the water expands when heated and can reveal underlying pressure issues or a faulty expansion vessel.
DIY fix possible
Check that the filling loop valves are fully closedBleed water from a radiator using a bleed key to reduce pressureMonitor the pressure gauge until it reaches approximately 1.5 barRestart the boiler