C(1) Low

Potterton C(1) Fault Code

Also written as C1 — same fault.

The Potterton C(1) fault code means: your boiler is currently turned off or the temperature dial is set too low to trigger the heating.. It appears on 3 Potterton models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Boiler thermostat set to ‘off’ or low setting

What causes the Potterton C(1) fault?

This status occurs because the control dial on the front of the boiler is positioned either at '0' or at a temperature too low to bridge the internal electrical circuit. It indicates that the appliance is receiving power but has not been given the instruction to begin the ignition sequence. This is typically a result of the dial being accidentally knocked or turned down during warmer weather.

This is frequently seen during the transition into autumn when homeowners forget the boiler was turned down over the summer months.

DIY fix possible

Locate the thermostat control dial on the front of the boilerTurn the dial clockwise to a higher setting or to the 'On' positionCheck that your wall thermostat is also turned up to call for heat

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Potterton models that show the C(1) fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Potterton C(1) 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