BoilerFaultCodesTechnical description
Failed temperature – try resetting the boiler
What causes this fault?
This fault occurs when the water inside the heat exchanger reaches an unsafe temperature, triggering a safety shutdown. It is usually caused by a lack of water flow, often due to a seized internal pump or a blockage within the system's pipework. If the pump cannot move the hot water away from the burner quickly enough, the heat builds up rapidly and trips the overheat sensor.
This issue often appears when the heating is first turned on after summer, as the circulation pump 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.
Find a Gas Safe engineer
Search the official register →