neon flashing (2nd instance) Medium

Potterton neon flashing (2nd instance) Fault Code

Also written as NEONFLASHING2NDINSTANCE — same fault.

The Potterton neon flashing (2nd instance) fault code means: your boiler is receiving conflicting signals about whether it should be running, which is causing it to restart its warm-up cycle repeatedly.. It appears on 1 Potterton model in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Preheating function starts after 25 seconds. Preheat control is not at minimum position. External control calling for heat. Go to section ‘L’.
Typical repair cost £120-250 (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 neon flashing (2nd instance) fault code

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

Source

Potterton neon flashing (2nd instance) 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