BoilerFaultCodesYour boiler has become too hot and has automatically shut itself down to prevent damage or safety issues.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The overheat thermostat has operated due to an overheat condition. It will require manual re-setting.
What causes this fault?
This fault occurs when the water inside the heat exchanger reaches a dangerously high temperature, triggering a safety switch to cut the power. The most common reasons are a failed pump that isn't moving water away from the boiler quickly enough or a blockage in the system pipework. It can also happen if the internal sensors fail and wrongly report that the boiler is boiling over.
This fault is more common when the heating is first turned on after summer, as circulating pumps often seize up during long periods of inactivity.
DIY fix possible
Locate the reset button on the front or underside of the boiler control panelPress the reset button firmly once to see if the red light goes out and the boiler restartsCheck that your radiator valves are open and that the pump is not making unusual grinding noises
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 Red LED illuminated (Overheat) — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Potterton Kingfisher MF RSL 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.