High
1 12 on Ariston Clas System 28

Your boiler's internal sensor that monitors the temperature of the water returning to the system is failing to send a signal, causing the unit to stop working for safety reasons.

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

C.H. Return temp. probe circuit open / short circuit

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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