BoilerFaultCodesTechnical description
Flow temperature sensor overheating due to a blocking fault or a lockout error – the valves of the radiator heating circuit may have an issue or the water pressure is low and needs filling
What causes this fault?
This fault occurs when the water inside the boiler heats up much faster than it can be moved away into your radiators. The most common reason is a lack of circulation, often caused by the pump failing, air being trapped in the system, or your radiator valves being closed. It can also be triggered if the system has lost too much water pressure to operate safely.
This fault is frequently seen in autumn when heating systems are 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.