How much does it cost to fix Potterton error code Lights: On Off Flash?

Typical repair cost for the Potterton Lights: On Off Flash fault is £90-150 including labour.

Lights: On Off Flash High

Potterton Lights: On Off Flash Fault Code

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

Your boiler is detecting that the electrical wires providing its power have been swapped around, which is preventing it from starting safely.

Also written as LIGHTSONOFFFLASH — same fault.

The Potterton Lights: On Off Flash fault code means: your boiler is detecting that the electrical wires providing its power have been swapped around, which is preventing it from starting safely.. It appears on 3 Potterton models in our database.

Technical description: Live & Neutral Reversed. Incoming Live and Neutral reversed.

Typical repair cost £90-150 (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 Lights: On Off Flash fault code

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

Source

Potterton Lights: 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 27 April 2026