How much does it cost to fix Ferroli error code F39?

Typical repair cost for the Ferroli F39 fault is £90-180 including labour.

F39 High

Ferroli F39 Fault Code

Q: What does the Ferroli F39 fault code mean?

Your boiler has sensed it is getting too hot too quickly and has shut down to protect its internal parts from damage.

The Ferroli F39 fault code means: your boiler has sensed it is getting too hot too quickly and has shut down to protect its internal parts from damage.. It appears on 14 Ferroli models in our database.

Technical description: Exchanger protection activation – possibly caused by no system circulation, air in the system or sensor damaged

What causes the Ferroli F39 fault?

This fault occurs when the boiler's internal components detect a rapid, unsafe rise in temperature that cannot be dissipated. It is usually caused by a blockage in the pipework, a buildup of air, or a pump that has failed and stopped moving water through the system. In some cases, the temperature sensor itself may be faulty and providing an incorrect reading to the control board.

This issue often surfaces when the heating is first turned on after summer, as circulation pumps can seize up during long periods of inactivity.

Typical repair cost £90-180 (including labour)

DIY fix possible

Check that your radiator valves are open and not turned to the off position.Ensure the boiler pressure is between 1.0 and 1.5 bar on the pressure gauge.Try bleeding your radiators to remove any trapped air that might be blocking water flow.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Ferroli models that show the F39 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ferroli F39 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