42 Medium

Grant 42 Fault Code

The Grant 42 fault code means: your boiler is struggling to get the fire started and is slowly adding extra fuel to help build a strong flame.. It appears on 1 Grant model 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: WAIT LIGHTING – LIGHTING FEED REDUCED: Period of time intermittent quantities of pellets supplied to the brazier to increase the flame.
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 42 fault code

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

Source

Grant 42 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