Lockout (Red) light flash High

Potterton Lockout (Red) light flash Fault Code

Also written as LOCKOUTREDLIGHTFLASH — same fault.

The Potterton Lockout (Red) light flash fault code means: your boiler has automatically turned itself off because internal sensors detected it was getting too hot, likely due to a flow restriction or a faulty sensor.. 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: Overheat Lockout - an overheat condition occurs
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 flash fault code

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

Source

Potterton Lockout (Red) light 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