BoilerFaultCodesTechnical 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.
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.