BoilerFaultCodesTechnical description
Safety temperature limiter has tripped.
What causes this fault?
This fault occurs when the water temperature inside your boiler exceeds a safe limit, causing the safety sensor to shut the system down to prevent damage. The most common reasons are a failed internal pump that isn't moving water away quickly enough or a buildup of sludge and limescale that is restricting flow through the heat exchanger.
This fault is more common in the autumn when heating systems are switched back on after a long summer break, as internal pumps can seize up due to 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.
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