High
EE0099 on Ariston Clas One

Your boiler's sensor that monitors water returning from your radiators is malfunctioning, which is causing the system to stop heating your home as a safety precaution.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Heating return temperature probe short circuited

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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