BoilerFaultCodesWhat the manual says
Manufacturer manualInsufficient system water pressure appliance operation
What causes this fault?
This fault occurs when the internal sensor detects that there isn't enough water pressure to safely circulate heat around your home. The most common reason is a slow leak somewhere in the radiator network or a drop in pressure following the bleeding of your radiators. In some cases, a component inside the boiler like the expansion vessel may have lost its charge, leaving the system unable to maintain steady levels.
This code is frequently seen at the start of autumn when homeowners turn their heating back on for the first time after summer, or after bleeding radiators for the winter 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 AL40: no call-out fees, no surprise bills.
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