Common problems guide

The most common Alpha 500e problems

The faults most likely to send a Alpha 500e into lockout — with plain-English causes, what to check first, estimated repair costs and whether you need a Gas Safe engineer.

This model is discontinued. Parts can be harder to source and expensive. If repair costs are mounting, a new A-rated boiler may be the smarter choice.

The 3 most common faults

01

Overheat thermostat High Engineer

Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage.

Est. cost: £120-220
Parts: Overheat thermostat, Central heating pump, Diverter valve

Full guide for Overheat thermostat

02

Red reset button illuminated High Engineer

Your boiler has stopped working because it failed to ignite, which could be due to a simple issue like a lost gas supply or a more complex internal fault.

Est. cost: £120-250
Parts: Ignition electrode, Gas valve, Printed Circuit Board

Full guide for Red reset button illuminated

03

White reset neon illuminated High Engineer

Your boiler has sensed a lack of water flow, which is preventing it from heating your home safely.

Est. cost: £150-250
Parts: Flow switch, Diverter valve diaphragm, Central heating pump

Full guide for White reset neon illuminated

Parts most often replaced

on the Alpha 500e

Overheat thermostatCentral heating pumpDiverter valvePCBIgnition electrodeGas valve

Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.

Call a Gas Safe engineer if…

You can smell gas or see signs of a leak
The Alpha shows an Emergency or High severity code
The boiler keeps locking out after repeated resets
You've tried the DIY checks and the fault hasn't cleared
There's visible water leaking from the boiler
The flame is yellow or orange instead of blue

See the full 3-code list for the Alpha 500e