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Neon B Flashing (every 5 seconds) on Alpha CD28

Your boiler is simply plugged in and switched on, which is normal operation rather than an actual fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Electricity supply to the boiler is on.

From this model's manual
Verified against the Alpha/Alpha Alpha Cb24 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Boiler cover options

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Related fault codes

Neon AView →Neon CView →

All 8 fault codes on the CD28

Seeing a different code? Every code this model can display, in one place.

Neon A and B Flashing on and off alternativelyNeon A and B Flashing on and off at the same timeNeon A Flashing on and offNeon A Illuminated continuouslyNeon B Flashing on and offNeon B Flashing very slowly (every 5 seconds)Neon B Illuminated continuously

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