BoilerFaultCodesTechnical description
Flow/return valves closed, Stuck pump. Boiler has overheated.
What causes this fault?
This fault occurs when the water inside the boiler gets too hot because it cannot flow away from the heat source quickly enough. The most common reasons are a pump that has seized up or internal valves being accidentally left closed, which traps the heat and triggers a safety shutdown.
This fault is more common in autumn when heating systems are switched back on for the first time after being idle all summer, which often leads to the pump seizing.
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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