BoilerFaultCodesTechnical description
Fuse F2 blown or temperature of burner thermostat too high or supply temperature too high.
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the unit is overheating or when an electrical surge has blown a protective fuse on the circuit board. It is often caused by a lack of water flow, a failing pump, or a build-up of debris blocking the heat exchanger, which prevents heat from being carried away from the burner. In some cases, the burner thermostat itself may have failed, incorrectly signaling a high-temperature situation.
This issue often surfaces at the start of autumn when the heating is turned back on after a long summer break, as pump components can seize during 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.