BoilerFaultCodesTechnical description
Overheat fault: The maximum temperature thermostat has operated.
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, causing the safety sensors to shut the system down to prevent damage. The most common reasons are a pump failure that stops water from moving or a blockage in the heat exchanger caused by a buildup of debris and limescale over time.
This issue often comes to light during the first cold snap of autumn when the heating is turned back on after being idle all summer, which can cause internal parts like the pump to seize.
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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