BoilerFaultCodesYour boiler has detected trapped air or a blockage that is stopping water from flowing through your heating system correctly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Air in the pump (restricted central heating flow)
What causes this fault?
This fault occurs when air becomes trapped inside the boiler's internal pump, preventing it from effectively pushing water around your radiators. The most common reason is a buildup of air pockets following a system drain-down or a failure of the automatic vent that is supposed to release these gases. In some cases, it can also be triggered by a heavy buildup of sludge or debris that has physically blocked the water's path.
This code is frequently seen in autumn when heating systems are turned back on after the summer and trapped air or settled debris begins to circulate.
DIY fix possible
Check that your boiler pressure is between 1.0 and 1.5 barBleed your radiators using a radiator key to remove trapped airEnsure all radiator valves and isolation valves under the boiler are fully openReset the boiler using the selector switch
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