305 High

Ariston 305 Fault Code

The Ariston 305 fault code means: your boiler's main control board has encountered an internal electronic error and needs to be reset.. It appears on 1 Ariston model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: All Boilers
Typical repair cost £250-450 (including labour)

DIY fix possible

Locate the Reset button on the front control panel.Press and hold the Reset button for five seconds.Wait for the boiler to complete its restart sequence.

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Ariston models that show the 305 fault code

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

Source

Ariston 305 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