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

Typical repair cost for the Potterton On * On Off fault is £150-250 including labour.

On * On Off High

Potterton On * On Off Fault Code

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

Your boiler has stopped working because a sensor that measures the water temperature is providing incorrect information, causing the system to shut down for safety.

Also written as ONONOFF — same fault.

The Potterton On * On Off fault code means: your boiler has stopped working because a sensor that measures the water temperature is providing incorrect information, causing the system to shut down for safety.. It appears on 1 Potterton model in our database.

Technical description: THERMISTOR

Typical repair cost £150-250 (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 Off fault code

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

Promax FSB 30HE Repair: £150-250

Source

Potterton On * On Off 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