High
4 green on Ferroli Combi 77 FF Popular

Your boiler's internal temperature sensors are stuck in a mode that is telling the system to stay on, which can lead to overheating or your heating staying on when it shouldn't.

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

Sensor (34) or (42) calling for heat

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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Related fault codes

7 greenView →

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