How much does it cost to fix Ariston error code 90 ●, red ●?

Typical repair cost for the Ariston 90 ●, red ● fault is £120-250 including labour.

90 ●, red ● High

Ariston 90 ●, red ● Fault Code

Q: What does the Ariston 90 ●, red ● fault code mean?

Your boiler has detected that it is running too hot and has automatically shut down to prevent damage to its internal systems.

Also written as 90RED — same fault.

The Ariston 90 ●, red ● fault code means: your boiler has detected that it is running too hot and has automatically shut down to prevent damage to its internal systems.. It appears on 1 Ariston model in our database.

Technical description: Overheat

Typical repair cost £120-250 (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 90 ●, red ● fault code

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

Clas One Repair: £120-250

Source

Ariston 90 ●, red ● 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