High
S.03 on Glow-worm Flexicom sx

Your boiler is failing to light the gas flame properly during its first stage of operation.

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

From this model's manual
Verified against the Glow Worm Flexicom 18sx installation & service manual, page 47.
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 control board sends a signal to start the fire, but it fails to detect a stable flame during the initial ignition sequence. The most common reasons are a worn-out spark electrode that can no longer create a spark, or a debris-clogged ignition lead preventing the electrical current from reaching the burner.

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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