How much does it cost to fix Ariston error code A 18?

Typical repair cost for the Ariston A 18 fault is £150-300 including labour.

A 18 High

Ariston A 18 Fault Code

Q: What does the Ariston A 18 fault code mean?

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

Also written as A18 — same fault.

The Ariston A 18 fault code means: your boiler is failing to stay lit because the flame keeps going out shortly after it starts.. It appears on 2 Ariston models in our database.

Technical description: 3 "flames in progress" disappearances in 1 operating cycle

Typical repair cost £150-300 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Ariston models that show the A 18 fault code

Click a model for the full fault code list and model-specific repair notes.

Euro Combi 30 MFFI Repair: £150-300
Euro Prisma 24 Repair: £150-300

Source

Ariston A 18 fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026