Medium
LED 6 yellow (0) [DHW mode] on Ferroli Arena

Your boiler is struggling to detect the temperature of your hot water because of a faulty connection or sensor, which means it will likely stop providing hot water until fixed.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Short circuit on D.H.W. sensor (42) or resistance lower than 500 Ohm

From this model's manual
Verified against the Ferroli Boiler Optima 201 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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