Red LED (Lockout) Emergency

Potterton Red LED (Lockout) Fault Code

Also written as REDLEDLOCKOUT — same fault.

The Potterton Red LED (Lockout) fault code means: your boiler has automatically shut down for safety because it has detected a blockage in the chimney or flue that prevents dangerous exhaust gases from escaping.. It appears on 2 Potterton models in our database.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description: The Products Discharge Safety Device (TTB) has operated due to a flue blockage (CF Models Only).
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 Red LED (Lockout) fault code

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

Source

Potterton Red LED (Lockout) 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