40 Low

Grant 40 Fault Code

The Grant 40 fault code means: your boiler is currently busy feeding wood pellets into the combustion chamber to get the fire started.. It appears on 1 Grant model 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: WAIT PRE LOAD BRAZIER: Initial loading of pellets into the brazier to enable combustion to start.

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 40 fault code

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

Source

Grant 40 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