BoilerFaultCodesTechnical description
Number of safety temperature cut off
What causes this fault?
This fault occurs when the boiler's internal safety sensors detect that the water temperature has risen too quickly or peaked beyond safe limits multiple times. It is usually caused by a lack of water flow, often due to a failing pump or a blockage of sludge and debris inside the main heating unit. Because the heat cannot be carried away into your radiators fast enough, the system shuts down to prevent the metal components from warping or cracking.
This issue often comes to light during the first cold spell of autumn, when a pump that has been idle all summer fails to start or struggles to push water through a cold, stagnant system.
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.