Boiler
F14
The F14 error code on a Ferroli boiler indicates a flow temperature sensor (NTC sensor) fault — specifically that the boiler is detecting an abnormal or missing signal from the primary circuit temperature sensor. This fault will lock out your boiler, leaving you without heating or hot water until it’s resolved.
What does this error mean?
Your Ferroli boiler constantly monitors water temperature using an NTC (Negative Temperature Coefficient) sensor on the flow pipe. When the boiler detects that this sensor is sending an out-of-range, erratic, or absent reading, it throws the F14 fault and shuts down as a safety precaution. This prevents the boiler from firing without accurate temperature data, which could otherwise lead to overheating or damage.
Est. repair cost
£80–£180 for NTC sensor replacement (parts + labour); PCB replacement if needed: £250–£450
🔍 Likely causes
🛠️ Step-by-step fix
Check your boiler’s pressure gauge — it should read between 1 and 1.5 bar when cold. If it’s below 1 bar, repressurise the system using the filling loop and try a reset.
Press and hold the reset button on your Ferroli boiler (usually marked with a flame and arrow icon) for 3–5 seconds. If the boiler fires up and runs normally, monitor it over the next 24 hours.
If the fault returns immediately after reset, do not attempt further DIY. The F14 code points to a sensor or wiring fault inside the boiler — this is not a homeowner repair.
Do not attempt to access internal boiler components, test the NTC sensor, or inspect the PCB yourself. Working on the gas appliance internals without Gas Safe registration is illegal and dangerous.
While waiting for an engineer, turn off the boiler to avoid repeated lockouts and check whether your system has a magnetic filter — if accessible externally, a blocked filter can contribute to poor flow and sensor faults.
Book a Gas Safe registered engineer and tell them: ‘My Ferroli boiler is showing fault code F14 — a flow NTC temperature sensor fault.’ This lets them bring the right parts and reduces call-out time.
📞 When to call a professional
If a single reset does not clear the F14 fault permanently, you need a Gas Safe registered engineer — there is no further safe DIY action for this fault code. Tell the engineer it’s an F14 fault on a Ferroli boiler, specifying your model if possible (e.g. Modena, Optimax, Agile), as NTC sensor part numbers vary by model. Do not attempt to bypass the sensor or override the lockout.
⚖️ Repair or replace?
An NTC sensor replacement on a Ferroli boiler typically costs £80–£180 including parts and labour, making it a worthwhile repair on a boiler under 10 years old. If your boiler is over 10–12 years old and has a history of faults, a new A-rated combi boiler installed will cost £1,800–£2,800 but will cut energy bills and come with a manufacturer warranty. For a boiler under a decade old with no prior history of PCB or heat exchanger issues, repair is the sensible choice.