BoilerFaultCodesTechnical description
Primary circulation fault (Ensure that primary circulation is OK & that there is no blockage)
What causes this fault?
This fault occurs when the boiler detects that water isn't flowing through the internal heat exchanger at the required speed, causing a rapid rise in temperature. The most common reasons are air bubbles trapped within the pump or a mechanical failure of the pump motor which prevents it from pushing water around your radiators. It can also happen if the system pressure is too low or if an internal valve has become stuck.
This issue is more frequent in autumn when heating systems are turned back on after being idle all summer, which often causes pump components to seize or air pockets to shift.
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.