BoilerFaultCodesTechnical description
Water shortage, temperature rise too quick
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the water temperature is rising much faster than the system can handle. The most common reason is a lack of circulation, often caused by a failing pump or a blockage in the pipework that prevents the heat from being moved away from the boiler quickly enough. It can also be triggered if there is air trapped in the heat exchanger or if the system water pressure has dropped too low.
This issue is frequently seen during the first cold spell of autumn when heating systems are turned back on after a long summer break, which can cause internal pump components to seize.
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.