BoilerFaultCodesYour boiler has temporarily paused because the water is not flowing through the system fast enough, causing it to heat up too quickly.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Appliance is within the waiting period of the modulation block/operation block function due to water shortage (flow-return spread too large)
What causes this fault?
This fault occurs when the water temperature increases too rapidly within the heat exchanger because it isn't moving through the pipes fast enough to carry the heat away. The most common reasons are a failing internal pump, a build-up of sludge blocking the narrow waterways, or air trapped within the system preventing proper circulation.
This issue is most common when you first switch the heating back on for autumn, as pump components can seize or sludge can settle after being inactive over the summer.
DIY fix possible
Check that all radiator valves (TRVs) are fully openEnsure the boiler pressure is between 1.0 and 1.5 bar on the displayCheck for any blocked magnetic filters or air locks in the radiators
Find a Gas Safe engineer
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