2 flashes green High

Main 2 flashes green Fault Code

Also written as 2FLASHESGREEN — same fault.

The Main 2 flashes green fault code means: your boiler has detected that an external safety control, such as a heating programmer or a smart thermostat, is not communicating with or is disconnected from the unit.. It appears on 1 Main model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Shutdown input: BL terminals on User Interaction Controller are open circuit
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 2 flashes green fault code

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

Source

Main 2 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