High
LED 4 (CH) on Ferroli Arena

Your boiler has detected an issue with its internal temperature sensing, meaning it cannot accurately judge how much to heat your radiators.

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.

What the manual says

Manufacturer manual

Central heating sensor (34) not connected or boiler temperature too high or boiler thermostat (61) below CH temperature.

From this model's manual
Verified against the Ferroli Boiler Optima 901 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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