BoilerFaultCodesFerroli F34 Fault Code
The Ferroli F34 fault code means: your boiler has stopped working because the electrical power supply coming into your home is currently too low for the system to operate safely.. It appears on 14 Ferroli models in our database.
Technical description: Supply voltage under 170V
What causes the Ferroli F34 fault?
This fault occurs when the electrical supply entering the boiler drops to a level that is too weak to power the internal components safely. The most common reason is an external issue with the local power grid, but it can also be triggered by a faulty control board inside the boiler that is misreading the incoming voltage.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ferroli models that show the F34 fault code
Click a model for the full fault code list and model-specific repair notes.
- Arean Repair: £120-250
- Arena 30A Repair: £100-200
- BlueHelix Pro 25C Repair: £100-350
- BlueHelix Pro 32C Repair: £100-350
- Bluehelix Tech Repair: £100-350
- Domi Compact Repair: £120-250
- Domiproject Repair: £100-£350
- Econcept 100 Repair: £120-250
- iBoiler 24 Repair: £100-350
- iBoiler 28 Repair: £90-250
- Maxima 35 S Repair: £120-250
- Modena HE Repair: £100-350
- Optima 201 Repair: £120-250
- Optimax Repair: £100-250
Source
Ferroli F34 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