Common problems guide

The most common Ariston Egis 24 MFFI problems

The faults most likely to send a Ariston Egis 24 MFFI 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 4 most common faults

01

Red L.E.D. I illuminated High Engineer

Your boiler has failed to start the flame after several attempts and has shut itself down as a safety precaution.

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

Full guide for Red L.E.D. I illuminated

02

Red LED I High Engineer

Your boiler has stopped working because it failed to light the flame needed to heat the water.

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

Full guide for Red LED I

03

Red LED I (Overheat) High Engineer

Your boiler has automatically turned itself off because it has detected that the water inside is getting dangerously hot.

Est. cost: £120-250
Parts: NTC sensor, Primary heat exchanger, Pump

Full guide for Red LED I (Overheat)

04

Yellow L.E.D. H illuminated Emergency Engineer

Your boiler has temporarily turned itself off because it is struggling to safely clear away waste gases, which could lead to harmful fumes building up if not addressed.

Est. cost: £120-250
Parts: Flue fan, Air pressure switch, Venturi

Full guide for Yellow L.E.D. H illuminated

Parts most often replaced

on the Ariston Egis 24 MFFI

Ignition electrodeGas valvePrinted Circuit BoardPrinted Circuit Board (PCB)NTC sensorPrimary heat exchanger

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 Ariston 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 4-code list for the Ariston Egis 24 MFFI