How much does it cost to fix Main error code 5 flashes green?

Typical repair cost for the Main 5 flashes green fault is £200-450 including labour.

5 flashes green High

Main 5 flashes green Fault Code

Q: What does the Main 5 flashes green fault code mean?

Your boiler's internal computer is experiencing a configuration error, which prevents it from knowing how to safely operate your heating and hot water.

Also written as 5FLASHESGREEN — same fault.

The Main 5 flashes green fault code means: your boiler's internal computer is experiencing a configuration error, which prevents it from knowing how to safely operate your heating and hot water.. It appears on 1 Main model in our database.

Technical description: Parameter fault: Parameter error or faulty PU, Configuration error or PCB fault

Typical repair cost £200-450 (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 5 flashes green fault code

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

Insul 7 Repair: £200-450

Source

Main 5 flashes green 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