Nefit fault code 4F
Fault code 4F on a Nefit boiler (including EcomLine) means: The temperature of the safety sensor is higher than 101C There is too much resistance in the central heating circuit, the bypass is incorrectly installed or set. Reset the appliance once. If the code comes back, a part is usually faulty, often a temperature sensor. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code 4F on a Nefit boiler indicates: The temperature of the safety sensor is higher than 101C There is too much resistance in the central heating circuit, the bypass is incorrectly installed or set. The safety sensor may be faulty or worn. The pump receives no voltage. Water level in the central heating circuit is too low.
Fixing fault code 4F: step by step
- Read the water pressure on the display or gauge. With the system cold it should be between 1.5 and 2 bar.
- Bleed the radiators with a radiator key, then check the pressure again and top up if needed.
- When there is a heat demand, feel or listen whether the pump is running (a light vibration or hum).
- Reset the appliance once. If the code comes straight back, do not keep resetting it.
- If the pump is not running, or the code comes back, the pump is seized or faulty.
Applies to
Nefit EcomLine, HR 11 Economy, HR 22, HR 22 Classic, HR 22 Excellent, HR 30 Excellent, HR 43, HR 43 Classic, HR 43 Excellent.
Fault code 4F on other Nefit series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- 4F on EcomLine, HR 30, HR 30 Classic: The temperature of the safety sensor is higher than 101 °C.
Matching parts
Nefit parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
Parts per Nefit-series: ProLine (NxT) · TrendLine (II) · EcomLine · TopLine.
Based on the cause, these original Nefit parts fit (always check the type number of your appliance):
- Nefit control sensor for EcomLine € 50.91
- Nefit sensor stainless steel safety for EcomLine € 93.55
- Nefit DHW sensor for EcomLine and TopLine € 25.95
Further reading on this cause
Other Nefit codes with the same cause
- 0Y 276 — The contacts of the flow sensor are open circuit
- 0Y 277 — The safety temperature sensor has measured a temperature higher than 95°C.
- 0Y 285 — The return sensor has measured a current central heating return water temperature higher…
- 1021 — Domestic hot water temperature sensor defective
- 1022 — The domestic hot water temperature sensor is defective
- 1065 — Pressure sensor defective or not connected.
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does Nefit boiler fault code 4F mean?
The temperature of the safety sensor is higher than 101C There is too much resistance in the central heating circuit, the bypass is incorrectly installed or set. The safety sensor may be faulty or worn. The pump receives no voltage. Water level in the central heating circuit is too low.
How do I fix fault code 4F on a Nefit boiler?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for Nefit fault code 4F?
That depends on the exact cause. In the Nefit parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code 4F myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All Nefit boiler faults and codes at a glance →