E 99 High

Ariston E 99 Fault Code

Also written as E99 — same fault.

The Ariston E 99 fault code means: your boiler has detected a series of internal faults and has locked itself down for safety reasons after multiple failed attempts to function.. It appears on 4 Ariston models 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: After the fifth attempt, the boiler goes into safety shutdown mode
Typical repair cost £120-300 (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 99 fault code

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

Source

Ariston E 99 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 7 July 2026