On Off Flash High

Potterton On Off Flash Fault Code

Also written as ONOFFFLASH — same fault.

The Potterton On Off Flash fault code means: your boiler has detected that the electricity supply wires are connected the wrong way around, which prevents it from operating safely.. It appears on 4 Potterton models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Live & Neutral Reversed. Incoming Live and Neutral reversed.
Typical repair cost £90-160 (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 Off Flash fault code

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

Source

Potterton On Off Flash 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 7 July 2026