High
LOCK OUT on Halstead Hero

Your boiler has stopped working for safety reasons and needs a manual reset to attempt to start up again.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Boiler failure to light or safety shut down; requires reset by turning the boiler thermostat fully anti-clockwise.

From this model's manual
Verified against the Halstead Hero installation & service manual, page 19.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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