Low
Neon B Flashing very slowly (every 5 seconds) on Alpha SY9 24

Your boiler is receiving power normally and is currently in standby mode waiting for a heating or hot water demand.

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 Sy9 24 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.

DIY fix possible

No action is required as this is a normal operational status light indicating the boiler is powered on.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like Neon B Flashing very slowly (every 5 seconds): no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

All 8 fault codes on the SY9 24

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 A Illuminated continuously and B flashingNeon B Flashing on and offNeon B Illuminated continuously

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on a combi.

Read →

Boiler won't turn on: 9-step checklist

Work through these before the call-out.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →