How much does it cost to fix Main error code 3 flashes green?

Typical repair cost for the Main 3 flashes green fault is £120-250 including labour.

3 flashes green High

Main 3 flashes green Fault Code

Q: What does the Main 3 flashes green fault code mean?

Your boiler has stopped because it cannot keep the internal fire lit, meaning you currently have no heating or hot water.

Also written as 3FLASHESGREEN — same fault.

The Main 3 flashes green fault code means: your boiler has stopped because it cannot keep the internal fire lit, meaning you currently have no heating or hot water.. It appears on 1 Main model in our database.

Technical description: Flame loss: No flame detected during operation

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 3 flashes green fault code

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

Insul 7 Repair: £120-250

Source

Main 3 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