High
F51 on Ferroli Bluehelix HiTech RRT

Your boiler has shut down because a temperature safety sensor has detected a potential overheating issue or has developed a fault itself.

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

Limit thermostat fault (parameter b06 = 1 or 4)

From this model's manual
Verified against the Ferroli Bluehelix Hitech Rrt 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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