How much does it cost to fix Potterton error code On On On On?

Typical repair cost for the Potterton On On On On fault is £120-200 including labour.

On On On On High

Potterton On On On On Fault Code

Q: What does the Potterton On On On On fault code mean?

Your boiler has detected that water is failing to drain away properly and has shut itself down to prevent internal flooding.

Also written as ONONONON — same fault.

The Potterton On On On On fault code means: your boiler has detected that water is failing to drain away properly and has shut itself down to prevent internal flooding.. It appears on 1 Potterton model in our database.

Technical description: Condensate pump level switch activated for longer than 3 minutes - boiler locks out.

Typical repair cost £120-200 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Potterton models that show the On On On On fault code

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

Promax FSB 30HE Repair: £120-200

Source

Potterton On On On On 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