GREEN blinking (0.5s) Medium

Grant GREEN blinking (0.5s) Fault Code

Also written as GREENBLINKING05S — same fault.

The Grant GREEN blinking (0.5s) fault code means: your boiler is currently undergoing a safety timing delay, which typically occurs after it has failed to ignite successfully on the first attempt.. It appears on 6 Grant models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Safety time
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 GREEN blinking (0.5s) fault code

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

Source

Grant GREEN 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 7 July 2026