BoilerFaultCodesPotterton C3 Fault Code
The Potterton C3 fault code means: your boiler is briefly pausing itself to prevent the system from turning on and off too frequently, which helps protect the internal parts from unnecessary wear.. It appears on 1 Potterton model in our database.
Technical description: Boiler restart delayed to prevent rapid cycling. (Max. delay time is 5 mm)
What causes the Potterton C3 fault?
This occurs when your thermostat tells the boiler to turn on too soon after it has just finished a heating cycle. To protect the internal components from the strain of constantly stopping and starting, the boiler forces a short pause to let the system stabilise. It is often caused by the radiators reaching their target temperature very quickly or a thermostat being set very close to the current room temperature.
This is more common during the milder 'shoulder' months of spring and autumn when the heating isn't needed constantly but kicks in for short bursts.
DIY fix possible
Wait for 5 minutes for the countdown to completeEnsure radiators are turned on to allow heat to circulateCheck that the room thermostat is set to a temperature higher than the current room temperature
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Gas Safe Register →Potterton models that show the C3 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton C3 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