High
EA on Worcester Bosch Greenstar 12i System

Your boiler has tried to light several times but has been unable to detect a flame, causing the system to shut down for safety.

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

No ionisation detected after ignition

From this model's manual
Verified against the Worcester Bosch Greenstar 12i System 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.

What causes this fault?

This fault occurs when the boiler's internal computer tries to start the burner multiple times but cannot confirm that a steady flame has been established. The most common reasons include a lack of gas supply to the unit, a blocked pipe that removes waste water, or dirty internal sensors that can no longer 'see' the flame effectively.

This fault is frequently seen during freezing winter temperatures, as the external condensate pipe can freeze solid, causing water to back up into the boiler and prevent it from lighting.

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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