BoilerFaultCodesTechnical description
Failed low water – pressure switch or pump, possible issue with pump, incorrect system pressure or the low water switch pressure needs replacing
What causes this fault?
This fault occurs when the boiler's internal sensors detect that water is not circulating correctly or the pressure has dropped too low to operate safely. The most common reason is a simple loss of water pressure in the central heating system, but it can also be caused by a mechanical failure of the pump or a faulty sensor that is incorrectly reporting low pressure.
This issue often surfaces when the heating is turned back on for autumn, as stagnant pumps can seize or system pressure may have dropped during a summer of inactivity.
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.