Common problems guide

The most common Ariston Euro Combi 30 MFFI problems

The faults most likely to send a Ariston Euro Combi 30 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.
26 documented codes
6 most common
2 DIY-safe checks
4 engineer needed

The 6 most common faults

01
E02 High DIY-safe

Your boiler has stopped working because the water pressure inside the heating system has dropped too low.

What to try first

Locate the filling loop, which is usually a metal braided hose underneath the boiler.Open the valves on the filling loop to allow cold mains water into the system.Watch the pressure gauge on the front of the boiler until it reaches 1.5 bar, then securely close the valves.

Est. cost
£80-120
Parts
Pressure relief valve, Pressure gauge, Expansion vessel
Full guide for E02
02
E 08 High DIY-safe

Your boiler has detected that the water level inside the heating system is too low to operate safely.

What to try first

Locate the filling loop, which is usually a silver braided hose under the boiler connected to two valves.Slowly open the valves to allow mains water into your heating system.Watch the pressure gauge on the front of the boiler until it reaches the green zone, typically between 1.0 and 1.5 bar.Close both valves tightly and restart the boiler.

Est. cost
£80-150
Parts
Filling loop, Pressure relief valve, Pressure sensor
Full guide for E 08
03
E04 High Engineer

Your boiler is trying to start but the flame is failing to ignite or stay alight, so it has shut down as a safety precaution.

Est. cost
£120-250
Parts
Ignition electrode, Gas valve, Circuit board (PCB)
Full guide for E04
04
A03 High Engineer

Your boiler has failed to ignite the flame reliably and has stopped trying for your safety.

Est. cost
£120-250
Parts
Ignition electrode, Ionisation probe, Gas valve
Full guide for A03
05
A01 High Engineer

Your boiler has detected that it has become too hot and has automatically shut itself down to prevent damage.

Est. cost
£120-250
Parts
Overheat thermostat, NTC sensor, Primary heat exchanger
Full guide for A01
06
A 18 High Engineer

Your boiler is failing to stay lit because the flame keeps going out shortly after it starts.

Est. cost
£150-300
Parts
Flame rectification electrode, Gas valve, Ignition lead
Full guide for A 18
Parts most often replaced

on the Ariston Euro Combi 30 MFFI

Pressure relief valvePressure gaugeExpansion vesselFilling loopPressure sensorIgnition 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 26-code list for the Ariston Euro Combi 30 MFFI

Related guides

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