How much does it cost to fix Main error code 6 flashes red?

Typical repair cost for the Main 6 flashes red fault is £120-250 including labour.

6 flashes red High

Main 6 flashes red Fault Code

Q: What does the Main 6 flashes red fault code mean?

Your boiler is having trouble communicating internally, which is causing it to shut down for safety reasons.

Also written as 6FLASHESRED — same fault.

The Main 6 flashes red fault code means: your boiler is having trouble communicating internally, which is causing it to shut down for safety reasons.. It appears on 1 Main model in our database.

Technical description: Miscellaneous (Bad connection or wiring fault internal or external to the boiler, Parameter error, Communication error)

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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Main models that show the 6 flashes red fault code

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

Insul 7 Repair: £120-250

Source

Main 6 flashes red 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