High
Neon 1 NOT lit on Glow-worm Glow-worm Micron 100FF 120FF

Your boiler is not receiving power, which means it cannot turn on to provide 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

Fault with mains supply or PCB fuse

From this model's manual
Verified against the Ultimate 100ff 120ff 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 control system is completely deprived of electrical power, often due to a blown internal fuse or a failure within the main circuit board. The most common reason is an electrical surge or a faulty internal component causing a short circuit, which trips the protection to prevent further damage.

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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