How much does it cost to fix Ariston error code E 33?

Typical repair cost for the Ariston E 33 fault is £100-200 including labour.

E 33 Medium

Ariston E 33 Fault Code

Q: What does the Ariston E 33 fault code mean?

Your boiler has stopped because it thinks a safety switch connected to your underfloor heating has been triggered or disconnected.

Also written as E33 — same fault.

The Ariston E 33 fault code means: your boiler has stopped because it thinks a safety switch connected to your underfloor heating has been triggered or disconnected.. It appears on 2 Ariston models in our database.

Technical description: Floor heating thermostat open circuit (if fitted) (ROOM THERMOSTATFLOOR)

Typical repair cost £100-200 (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 E 33 fault code

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

Source

Ariston E 33 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