BoilerFaultCodesYour boiler has stopped working because it has detected that the water inside is getting too hot.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Water temperature
What causes this fault?
This fault occurs when the water temperature inside the boiler exceeds a safe limit, causing the system to shut down to prevent damage. The most common reason is that water isn't moving through the unit quickly enough, often due to a pump failure or a blockage caused by sludge buildup in the pipework.
This issue often surfaces when the heating is first turned on after summer, as the internal pump can seize or become stuck during long periods of inactivity.
DIY fix possible
Check that all radiator valves are fully openEnsure there is enough water pressure by checking the gauge is between 1 and 1.5 barPress the reset button on the front of the boiler
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 4 — no call-out fees, no surprises.
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Ideal Maximiser SE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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