C Unknown

Main C Fault Code

The Main C fault code indicates a fault on your boiler. It appears on 2 Main models in our database.

Technical description: A fault on the boiler temperature sensor is indicated.

Engineer required

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

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Main models that show the C fault code

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

Source

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

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026