BoilerFaultCodesPotterton Red LED illuminated (Overheat) Fault Code
Also written as REDLEDILLUMINATEDOVERHEAT — same fault.
The Potterton Red LED illuminated (Overheat) fault code means: your boiler has become too hot and has automatically shut itself down to prevent damage or safety issues.. It appears on 2 Potterton models in our database.
Technical description: The overheat thermostat has operated and requires manual re-setting. An overheat condition has occurred.
What causes the Potterton Red LED illuminated (Overheat) 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
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Gas Safe Register →Potterton models that show the Red LED illuminated (Overheat) fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Red LED illuminated (Overheat) fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026