How much does it cost to fix Ariston error code A 39?

Typical repair cost for the Ariston A 39 fault is £250-450 including labour.

A 39 High

Ariston A 39 Fault Code

Q: What does the Ariston A 39 fault code mean?

Your boiler's main internal computer has detected a critical electronic error that is preventing it from functioning correctly.

Also written as A39 — same fault.

The Ariston A 39 fault code means: your boiler's main internal computer has detected a critical electronic error that is preventing it from functioning correctly.. It appears on 2 Ariston models in our database.

Technical description: MCU fault 1

Typical repair cost £250-450 (including labour)

Engineer required

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

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Ariston models that show the A 39 fault code

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

Euro Combi 30 MFFI Repair: £250-450
Euro Prisma 24 Repair: £250-450

Source

Ariston A 39 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