BoilerFaultCodesYour boiler has paused because the water temperature inside it has risen too quickly, which is usually caused by restricted water flow.
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Boiler shut down on a controlled stop (flow set point exceeded by 5°C)
What causes this fault?
This fault occurs when the water inside the boiler heats up much faster than it can be moved away into your radiators. The most common reason is a blockage or a failing pump that prevents the water from circulating properly, causing the system to pause to prevent overheating. It can also be triggered by trapped air or closed radiator valves restricting the path of the water.
This issue is most common when the heating is first turned on after summer, as pump components can seize during long periods of inactivity.
DIY fix possible
Check that all radiator valves (TRVs) are turned up to the maximum setting.Ensure the boiler pressure is between 1.0 and 1.5 bar on the gauge.Check if any bypass valves or external pumps are switched off or obstructed.
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 8 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Remeha Avanta 18V 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.
Affiliate links — we may earn a commission at no extra cost to you.