BoilerFaultCodesTechnical description
Overheat fault - Safety thermostat has activated
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to shut the system down to prevent damage. The most common reasons are a failed pump that isn't moving water away from the heat exchanger quickly enough, or a blockage caused by a build-up of debris and sludge within the system.
This fault is more frequent when you first turn the heating back on for autumn, as pumps can seize up after being idle 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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