High
3 flashes red on Main Insul 7

Your boiler is trying to start up but is failing to light the internal flame, which means you currently have no heating or hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Ignition fault (No ignition, No flame detected following ignition, False flame signal detected, Repeated loss of flame detected)

From this model's manual
Verified against the Main Boiler Ins 3 9 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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