Ferroli C RY4 Fault Code
Also written as CRY4 — same fault.
The Ferroli C RY4 fault code means: your boiler has detected an internal communication error between its safety sensors and the fan, preventing it from safely starting up.. It appears on 4 Ferroli models in our database.
Technical description: Relay not energised - Air pressure switch (43) not in NC position or miswired: check wiring; fan (16) at low speed remove jumper JP4
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ferroli models that show the C RY4 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ferroli C RY4 fault code information on this page is sourced and cross-checked against the official Ferroli service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026