How much does it cost to fix Ariston error code 3 0 5?

Typical repair cost for the Ariston 3 0 5 fault is £200-450 including labour.

3 0 5 High

Ariston 3 0 5 Fault Code

Q: What does the Ariston 3 0 5 fault code mean?

Your boiler's internal computer is experiencing a software glitch or communication error that is preventing it from operating correctly.

Also written as 305 — same fault.

The Ariston 3 0 5 fault code means: your boiler's internal computer is experiencing a software glitch or communication error that is preventing it from operating correctly.. It appears on 1 Ariston model in our database.

Technical description: Main board error

Typical repair cost £200-450 (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 3 0 5 fault code

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

HS Premium Repair: £200-450

Source

Ariston 3 0 5 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