Common problems guide

The most common Ariston Genus 30 Plus problems

The faults most likely to send a Ariston Genus 30 Plus 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.
10 documented codes
6 most common
1 DIY-safe checks
5 engineer needed

The 6 most common faults

01
5 High DIY-safe

Your boiler has detected an incorrect water pressure level in the heating system, which usually means it needs more water added or has a minor leak.

What to try first

Locate the filling loop beneath your boiler.Open the valves slowly to let water into the system until the pressure gauge reads between 1 and 1.5 bar.Close the valves firmly and check for any visible leaks on your radiators or pipework.

Est. cost
£80-250
Parts
Filling loop, Expansion vessel, Pressure relief valve
Full guide for 5
02
6 High Engineer

Your boiler keeps safely shutting down because it is struggling to reliably detect the burner flame.

Est. cost
£90-180
Parts
Flame detection electrode, Ignition lead, PCB
Full guide for 6
03
7 High Engineer

Your boiler has automatically shut down because it detected that the internal water is getting dangerously hot, which usually points to poor water flow or trapped air.

Est. cost
£150-300
Parts
Safety thermostat, NTC temperature sensor, Circulating pump
Full guide for 7
04
30 40 50 60 70 80 Emergency Engineer

Your boiler has automatically shut down because it has detected dangerously high internal temperatures.

Est. cost
£150-350
Parts
Pump, NTC thermistor, PCB
Full guide for 30 40 50 60 70 80
05
1 Medium Engineer

Your boiler's burner keeps shutting off while you are trying to run hot water, meaning your taps might go cold.

Est. cost
£100-250
Parts
DHW flow switch, NTC temperature probe
Full guide for 1
06
3 Medium Engineer

Your boiler is struggling to keep your hot water warm enough while you are running the taps.

Est. cost
£150-300
Parts
NTC Temperature Sensor, Flow Meter, Diverter Valve
Full guide for 3
Parts most often replaced

on the Ariston Genus 30 Plus

Filling loopExpansion vesselPressure relief valveFlame detection electrodeIgnition leadPCB

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 10-code list for the Ariston Genus 30 Plus

Related guides

Boiler losing pressure → No hot water → When to replace → Symptom checker →