BoilerFaultCodesWhat the manual says
Manufacturer manualWater is leaking or the pump needs replacing or freeing due to the pump running dry.
What causes this fault?
This fault occurs when the boiler detects a serious lack of water pressure or circulation, often caused by a leak within the system or a failing internal pump. If the pump is spinning without enough water (running dry) or has become seized with debris, the boiler will shut down to prevent the components from overheating or burning out. In some cases, a faulty air vent can also cause an air lock that tricks the sensors into thinking the system is empty.
This issue is frequently seen in autumn when heating systems are switched back on after a long summer break, as pumps are more likely to seize if they haven't been used for several months.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Avoid the next call-out bill
A cover plan would handle faults like A1: no call-out fees, no surprise bills.
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