n6 High

Protherm n6 Fault Code

Also written as N6 — same fault.

The Protherm n6 fault code means: your boiler has detected that the water flow inside the system is restricted or blocked, preventing it from heating your home properly.. It appears on 1 Protherm model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: 22 kW (75 064 Btu/hr)
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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Protherm models that show the n6 fault code

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

Source

Protherm n6 fault code information on this page is sourced and cross-checked against the official Protherm service / installation manuals for each affected model.

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