Lockout (Red) light will flash High

Potterton Lockout (Red) light will flash Fault Code

Also written as LOCKOUTREDLIGHTWILLFLASH — same fault.

The Potterton Lockout (Red) light will flash fault code means: your boiler has detected that it is running too hot and has automatically shut down to prevent damage, meaning you currently have no heating or hot water.. It appears on 1 Potterton model 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: An overheat condition has occurred; boiler requires re-setting
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 Lockout (Red) light will flash fault code

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

Source

Potterton Lockout (Red) light will 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