BoilerFaultCodesPotterton C.(2) Fault Code
Also written as C2 — same fault.
The Potterton C.(2) fault code means: your boiler's pilot light is on, but the main burner is not firing up because your external heating controls are not telling the boiler to start.. It appears on 3 Potterton models in our database.
Technical description: Main burner fails to light, pilot burning - Additional controls not calling for heat.
What causes the Potterton C.(2) fault?
This issue occurs because the boiler is waiting for a signal from your external equipment that never arrives. Even though the boiler is ready to work, the wall thermostat, timer, or a motorised valve in your airing cupboard has likely failed or reached its target temperature and isn't sending the 'start' command. It means the boiler itself is often healthy, but the system's brain or its switching components have lost communication.
This fault often surfaces during the first cold snap of autumn when controls that have been dormant all summer are suddenly required to operate.
DIY fix possible
Check that your wall thermostat is turned up higher than the current room temperature.Ensure your programmer or heating timer is set to 'On' or 'Auto'.Check if the batteries in your wireless thermostat need replacing.
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Gas Safe Register →Potterton models that show the C.(2) fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton C.(2) 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