LOCK OUT High

Halstead LOCK OUT Fault Code

Also written as LOCKOUT — same fault.

The Halstead LOCK OUT fault code means: your boiler has stopped working for safety reasons and needs a manual reset to attempt to start up again.. It appears on 1 Halstead 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: Boiler failure to light or safety shut down; requires reset by turning the boiler thermostat fully anti-clockwise.
Typical repair cost £100-250 (including labour)

DIY fix possible

Turn your boiler thermostat dial fully anti-clockwise to the reset position and hold it there for a few seconds.Turn the dial clockwise back to your desired temperature setting.Wait a few minutes to see if the boiler ignites and the flame icon appears.

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Halstead models that show the LOCK OUT fault code

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

Source

Halstead LOCK OUT fault code information on this page is sourced and cross-checked against the official Halstead service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026