BoilerFaultCodesTechnical description
2 lights flashing slowly (Primary Overheat)
What causes this fault?
This fault occurs when the water inside the heat exchanger exceeds a safe temperature, triggering a safety sensor to cut the power. The most common reasons are a failed pump that isn't moving water away fast enough or a physical blockage in the system causing the unit to get too hot too quickly.
This fault often appears during the first cold spell of autumn when the heating is turned on after being dormant all summer, which can cause internal pump components 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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