Common problems guide

The most common Ariston Euro Prisma 24 problems

The faults most likely to send a Ariston Euro Prisma 24 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
6 DIY-safe checks
0 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
Ignition Lockout High DIY-safe

Your boiler is failing to light the gas flame, which means you currently have no heating or hot water.

What to try first

Check if your gas meter has credit and the isolation valve is open.Try resetting the boiler by pressing the 'Reset' button on the front panel.Verify that other gas appliances in your home, like a hob, are working correctly.

Est. cost
£100-300
Parts
Ignition Electrode, Gas Valve, Printed Circuit Board (PCB)
Full guide for Ignition Lockout
03
L.E.D. D High DIY-safe

Your boiler has detected that water is not moving through the system properly, which is often caused by low water pressure.

What to try first

Check the pressure gauge on the front of the boilerIf the needle is below 1 bar, use the filling loop valves to top up the pressure to 1.5 barRestart the boiler using the reset button

Est. cost
£100-280
Parts
Circulation Pump, Primary Pressure Switch, Expansion Vessel
Full guide for L.E.D. D
04
L.E.D. G High DIY-safe

Your boiler has sensed it is getting too hot and has shut itself down for safety.

What to try first

Check that all radiator valves are fully open to allow water to circulate.Ensure there is enough water pressure indicated on the gauge (usually 1.0 to 1.5 bar).Turn the selector switch to the reset position for a few seconds, then back to the on position.

Est. cost
£90-280
Parts
Circulation pump, Overheat thermostat, Main heat exchanger
Full guide for L.E.D. G
05
Safety Shut-off High DIY-safe

Your boiler has performed a self-diagnostic check and stopped working because it detected an internal error that requires a reset or professional inspection.

What to try first

Press the 'Reset' button on the front control panelSwitch the electricity supply to the boiler off and back on after 30 secondsCheck that your gas pre-payment meter (if applicable) has credit

Est. cost
£100-£350
Parts
Printed Circuit Board (PCB), Ignition Electrodes, Gas Valve
Full guide for Safety Shut-off
06
INSUFFICIENT WATER High DIY-safe

Your boiler has detected that the water pressure is too low to operate safely, causing it to shut down.

What to try first

Locate the filling loop (a flexible silver hose) underneath or near the boiler.Slowly open the one or two taps on the hose until you hear water flowing.Watch the pressure gauge until it reaches between 1 and 1.5 bar, then close the taps tightly.Reset the boiler using the reset button or by switching it off and on.

Est. cost
£80-160
Parts
Filling loop, Water pressure switch, Expansion vessel
Full guide for INSUFFICIENT WATER

on the Ariston Euro Prisma 24

Pressure relief valvePressure gaugeExpansion vesselIgnition ElectrodeGas ValvePrinted Circuit Board (PCB)

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 Prisma 24