BoilerFaultCodesGrant Green blinking light Fault Code
Also written as GREENBLINKINGLIGHT — same fault.
The Grant Green blinking light fault code means: your boiler is struggling to burn fuel correctly because the balance of air is incorrect or a sensor is faulty.. It appears on 1 Grant model in our database.
Technical description: Set the air according to the instructions of the manual or replace
What causes the Grant Green blinking light fault?
This fault occurs when the boiler's internal computer detects that the flame is not burning steadily or efficiently. It is usually caused by a blockage in the fuel nozzle, a worn-out component in the air supply system, or a dirty sensor that can no longer 'see' the flame effectively. When the air and fuel mix is incorrect, the boiler enters a safety mode to prevent damage or soot build-up.
This issue often surfaces during the first cold snap of autumn when the boiler is worked harder after sitting idle all summer, allowing old fuel or debris to clog the nozzle.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Grant models that show the Green blinking light fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Grant Green blinking light 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