How much does it cost to fix Ariston error code S 04?

Typical repair cost for the Ariston S 04 fault is £120-200 including labour.

S 04 High

Ariston S 04 Fault Code

Q: What does the Ariston S 04 fault code mean?

Your boiler is currently unable to sense the temperature of your hot water properly, which means it will stop providing hot water until the faulty sensor is fixed.

Also written as S04 — same fault.

The Ariston S 04 fault code means: your boiler is currently unable to sense the temperature of your hot water properly, which means it will stop providing hot water until the faulty sensor is fixed.. It appears on 5 Ariston models in our database.

Technical description: Open circuit on Domestic hot water sensor

Typical repair cost £120-200 (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 S 04 fault code

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

Source

Ariston S 04 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