H n Medium

Evo H n Fault Code

Also written as HN — same fault.

The Evo H n fault code means: your boiler is displaying a service notification or a specific lockout state that requires a professional to check the internal sequence and settings.. It appears on 1 Evo 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: ALTERNATING 'H' 'n' - REFER TO FRAME 72
Typical repair cost £90-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Evo models that show the H n fault code

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

Source

Evo H n fault code information on this page is sourced and cross-checked against the official Evo service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026