BoilerFaultCodesTechnical description
Burner fault: Flow switch has not responded
What causes this fault?
This fault occurs when the boiler's internal sensors fail to detect water circulating through the heat exchanger after the pump has started. The most common cause is a seized pump or a blockage in the pipework that prevents the flow switch from physically moving into the 'on' position. If the boiler cannot confirm that water is moving to carry heat away, it shuts down immediately to prevent the unit from melting or exploding.
This issue is more frequent in autumn when the heating is turned on for the first time after summer, as internal pump components can seize up during long periods 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.