BoilerFaultCodesYour boiler is heating up much too fast because there isn't enough water moving through the system to carry the heat away.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Water shortage, temperature rise too quick
What causes this fault?
This fault occurs when the heat inside the boiler builds up much faster than the water can carry it away to your radiators. The most common reasons are a pump that has failed or become stuck, a significant blockage of sludge in the pipework, or air trapped within the system. Essentially, the boiler is forced to shut down to prevent itself from overheating.
This issue is frequently seen during the first cold spell of autumn when the heating is turned back on after being idle all summer, which can cause the pump to seize.
DIY fix possible
Check the pressure gauge and top up the water to between 1 and 1.5 bar using the filling loopEnsure all radiator valves and isolation valves under the boiler are fully openBleed your radiators to remove any trapped air pockets
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