What does the Keston 4 nn fault code mean?

Your boiler has detected an issue with the heating zone for a specific part of your home, and the burner is not operating correctly for that section.

How much does it cost to fix Keston error code 4 nn?

Typical repair cost for the Keston 4 nn fault is £150-350 including labour.

Module burning for zone 2

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Safety-critical — turn off, read this.

7 signs repair isn't worth it anymore.

Break-even maths on monthly cover.