High
Red light flashes on Glow-worm Swiftflow 100

Your boiler has entered a safety lockout mode and has stopped running to protect its internal components.

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

Indicates a lockout condition; momentarily interrupt the electrical supply to reset.

From this model's manual
Verified against the Swift Flow 100 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 fails to detect a flame after several attempts, causing it to shut down for safety. The most common reasons include a worn-out ignition spark that can no longer light the gas, or a faulty gas valve that isn't letting fuel into the burner. In some cases, the internal control board may be failing to send the correct electrical signals to start the sequence.

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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Avoid the next call-out bill

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