BoilerFaultCodesPotterton Red LED illuminated Fault Code
Also written as REDLEDILLUMINATED — same fault.
The Potterton Red LED illuminated fault code means: your boiler has become too hot and has automatically shut itself down as a safety precaution.. It appears on 3 Potterton models in our database.
Technical description: Overheat thermostat condition: It will require manual re-setting if an overheat condition occurs.
What causes the Potterton Red LED illuminated fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit, causing the safety sensor to cut the power. The most common reasons are a pump failure that prevents water from moving through the system or a build-up of sludge and debris blocking the internal pipework.
This issue is more frequent when the heating is first switched on after summer, as circulation pumps can seize up during long periods of inactivity.
DIY fix possible
Locate the reset button on the control panel, usually hidden under a small plastic cap or recessed.Press the reset button firmly to clear the lockout.Check that your radiator valves are open and that the pump is running to prevent it from overheating again.
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Potterton models that show the Red LED illuminated fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Red LED illuminated fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
- Potterton Kingfisher MF 40-100 manual (PDF)
- Potterton Kingfisher MF RSL manual (PDF)
- Potterton Kingfisher MF RSL/CFL manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026