High
Safety Lockout (Red LED) on Halstead Ace

Your boiler has stopped working because it failed to start, which could be due to a simple supply issue or a more complex internal fault.

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

Burner has failed to light and gone to ignition lock-out and possibly overheat cut-out.

From this model's manual
Verified against the Halstead Ace Gcno.47 333 10 1 installation & service manual.
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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