How much does it cost to fix Main error code 15?

Typical repair cost for the Main 15 fault is £150-300 including labour.

15 High

Main 15 Fault Code

Q: What does the Main 15 fault code mean?

Your boiler has detected a communication error between its internal electronic parts, causing it to shut down for safety.

The Main 15 fault code means: your boiler has detected a communication error between its internal electronic parts, causing it to shut down for safety.. It appears on 1 Main model in our database.

Technical description: Fault/flashing

Typical repair cost £150-300 (including labour)

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 15 fault code

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

Insul 7 Repair: £150-300

Source

Main 15 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 27 April 2026