BoilerFaultCodesPotterton C(3) Fault Code
Also written as C3 — same fault.
The Potterton C(3) fault code means: your boiler is unable to light the gas burner because a safety control valve inside the unit has stopped working.. It appears on 3 Potterton models in our database.
Technical description: Honeywell Control solenoid valve failed.
What causes the Potterton C(3) fault?
This fault occurs when the main gas control valve fails to open, preventing fuel from reaching the burner to create a flame. The most common reason is that the internal electrical coil has burnt out or the mechanical valve has become stuck due to age and wear. This acts as a safety shutdown to ensure gas does not flow when it cannot be safely ignited.
This failure is more frequent during the first cold snap of autumn, as the internal components can seize up after being inactive throughout the summer months.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Potterton models that show the C(3) fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton C(3) 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