Nefit fault code 4U 522
Fault code 4U 522 on a Nefit boiler (including ProLine) means: A sensor test is being carried out. The boiler waits until the test has passed. 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 4U 522 on a Nefit boiler indicates: A sensor test is being carried out. The boiler waits until the test has passed.
Applies to
Nefit ProLine, HRC 24 CW3, HRC 24 CW4, HRC 30 CW5.
Fault code 4U 522 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:
- 4U 522 on ProLine, NxT HRC 24 CW3, NxT HRC 24 CW4, NxT HRC 30 CW5: A sensor test is being carried out.
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 pressure sensor with click connection for TopLine and ProLine etc. € 74.49
- Nefit flow / return sensor for ProLine and TrendLine € 17.65
- Nefit flow sensor for TrendLine and ProLine etc. € 17.65
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 4U 522 mean?
A sensor test is being carried out. The boiler waits until the test has passed.
How do I fix fault code 4U 522 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 4U 522?
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 4U 522 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 →