GREEN ORANGE blinking (0.5s) Low

Grant GREEN ORANGE blinking (0.5s) Fault Code

Also written as GREENORANGEBLINKING05S — same fault.

The Grant GREEN ORANGE blinking (0.5s) fault code means: your boiler is currently preparing itself to ignite by clearing out the combustion chamber, which is a normal part of the startup cycle.. It appears on 5 Grant models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Pre-purge

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 GREEN ORANGE blinking (0.5s) fault code

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

Source

Grant GREEN ORANGE blinking (0.5s) 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 27 April 2026