Common problems guide

The most common Ariston Genus problems

The faults most likely to send a Ariston Genus 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 6 most common faults

01

E03 High Engineer

Your boiler is struggling to clear air or smoke properly, so it has safely shut itself down to prevent any unsafe operation.

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

Full guide for E03

02

E02 High Engineer

Your boiler is struggling to clear exhaust gases effectively, so it has safely shut itself down to prevent any risk of fumes entering your home.

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

Full guide for E02

03

E02 071 High Engineer

Your boiler is struggling to clear exhaust gases due to a sensor fault or exterior blockage, so it has safely shut itself down to prevent carbon monoxide buildup.

Est. cost: £150-250
Parts: Air pressure switch, Flue fan, Venturi tube

Full guide for E02 071

04

E02 078 High Engineer

Your boiler is failing to ignite the main burner, which means it cannot produce the flame required to provide heating or hot water.

Est. cost: £150-300
Parts: Ignition electrode, Gas valve, Flame rectification probe

Full guide for E02 078

05

A01 High Engineer

Your boiler is trying to start but cannot get the flame lit, so it has shut itself down as a safety precaution.

Est. cost: £120-250
Parts: Ignition electrode, Gas valve, PCB

Full guide for A01

06

A03 High Engineer

Your boiler has detected that it is overheating and has shut itself down as a safety precaution to prevent damage.

Est. cost: £150-300
Parts: NTC temperature sensor, Circulation pump, Heat exchanger

Full guide for A03

Parts most often replaced

on the Ariston Genus

Air pressure switchFlue fanVenturiFlue fan assemblyVenturi tubeIgnition electrode

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 17-code list for the Ariston Genus