Your boiler has become too hot and has automatically shut down as a safety precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Indicates the overheat thermostat has operated. Fault will be rectified by allowing the boiler to cool and turning the selector switch to the reset position.
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature, causing the system to shut down to prevent damage. The most common reasons are a pump failure that stops water from moving or a blockage in the heat exchanger that restricts flow. It can also be caused by a faulty internal sensor that is incorrectly reporting the temperature.
This fault is frequently seen when the heating is first turned on after summer, as the internal pump can often seize or stick during long periods of inactivity.
DIY fix possible
Wait at least 30 minutes for the boiler to cool down completely.Turn the main selector switch to the 'Reset' position and hold for 5 seconds.Turn the switch back to the 'On' position and check if the burner reignites.Ensure all radiator valves are open and the system pressure is between 1 and 1.5 bar.
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 Burner Neon (Flashing) — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Potterton Performa 24 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.