Lock-out (Red neon) High

Grant Lock-out (Red neon) Fault Code

Also written as LOCKOUTREDNEON — same fault.

The Grant Lock-out (Red neon) fault code means: your boiler has stopped working because the flame inside failed to light or stay on.. It appears on 1 Grant 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: Burner has failed to ignite or flame has been lost. Press the reset button on the burner control box if it is lit.
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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Grant models that show the Lock-out (Red neon) fault code

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

Source

Grant Lock-out (Red neon) fault code information on this page is sourced and cross-checked against the official Grant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026