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

b High Engineer

Your boiler has temporarily stopped working because it cannot safely confirm that exhaust gases are clearing properly.

Est. cost: £120-250
Parts: Air pressure switch, Flue assembly, PCB

Full guide for b

02

d High Engineer

Your boiler is struggling to detect the flow of water through the system, which typically means you will have no hot water or heating.

Est. cost: £120-250
Parts: Flow switch, Flow sensor, Wiring harness

Full guide for d

03

E High Engineer

Your boiler is failing to detect the burner flame, which stops it from working to keep your home warm and safe.

Est. cost: £100-250
Parts: Flame electrode/sensor, Ignition lead, Printed Circuit Board (PCB)

Full guide for E

04

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

05

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

06

E01 High Engineer

Your boiler has tried to start up several times but has failed to light the flame.

Est. cost: £100-£250
Parts: Ignition electrode, Gas valve, PCB

Full guide for E01

Parts most often replaced

on the Ariston Genus

Air pressure switchFlue assemblyPCBFlow switchFlow sensorWiring harness

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