BoilerFaultCodesTechnical description
Safety temperature limiter in heat exchanger or flue gas temperature limiter has operated
What causes this fault?
This fault occurs when the water inside the boiler or the exhaust gases reach a temperature that is no longer safe, triggering an automatic shutdown to prevent damage. The most common reasons are a pump failure that stops water from moving or a blockage in the system, such as a buildup of limescale or sludge, which causes the heat exchanger to trap too much heat.
This fault is more common when the heating is first turned back on in autumn, as internal pumps can seize up after being inactive throughout the summer.
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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