BoilerFaultCodesTechnical description
Temperature of safety sensor is rising too fast.
What causes this fault?
This fault occurs when the water inside the boiler heats up much faster than it can be moved away, leading to a sudden temperature spike that triggers a safety shutdown. The most common cause is a blockage or a failing pump preventing the water from circulating properly through your radiators. It can also be caused by a buildup of sludge or debris inside the heat exchanger, which restricts the flow of water.
This issue often surfaces in autumn when the heating is turned on for the first time after summer, as circulation pumps can seize or stick 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.