BoilerFaultCodesTechnical description
Safety switch-off: Temperature limiter - Maximum temperature at the flow/return temperature sensor is too high when the safety cut-out function is operating using the NTC
What causes this fault?
This fault occurs when the boiler's internal water temperature rises too quickly or exceeds a safe limit, triggering an emergency shutdown to prevent damage. The most common reasons are a seized pump failing to move water, a buildup of sludge blocking the heat exchanger, or air trapped within the system preventing proper circulation.
This issue often appears when the heating is first turned on after summer, as circulation pumps 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.