Nefit fault code 0Y 204
Fault code 0Y 204 on a Nefit boiler (including ProLine and TopLine) means: The boiler is waiting. The measured flow temperature is higher than the calculated or set heating water temperature. Reset the appliance once. If the code comes back, a part is usually faulty. 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 0Y 204 on a Nefit boiler indicates: The boiler is waiting. The measured flow temperature is higher than the calculated or set heating water temperature.
Fixing fault code 0Y 204: step by step
- Reset the appliance once; a one-off measuring error will then clear.
- Where you can reach it without opening the sealed combustion section, check that the sensor plug is seated firmly and the wiring is undamaged.
- If the code comes back, the sensor or its wiring is usually faulty (short or open circuit). Sensors in the sealed combustion section should be replaced by a qualified heating engineer.
Applies to
Nefit ProLine, TopLine, Aquapower HRC 25 CW4, Aquapower HRC 25 CW4 II, Aquapower HRC 25 CW5, Aquapower HRC 25 CW5 II, Aquapower HRC 30 CW5, Aquapower HRC 30 CW5 II, Aquapower HRC 45 CW6, Aquapower HRC 45 CW6 II.
Fault code 0Y 204 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:
- 0Y 204 on EcomLine, Elite HRC 24 CW4, Elite HRC 30 CW5: Operating phase Display test during the start-up phase.
- 0Y 204 on TrendLine, HRC 30 CW5, HRC 30 CW5 II: The boiler is waiting. The measured flow temperature is higher than the calculated or set central heating water temperature.
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.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Nefit pressure sensor with click connection for TopLine and ProLine etc. € 77.47
- Nefit automatic air vent € 27.18
- Nefit siphon gasket per 5 pcs for EcomLine and TopLine € 23.10
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 0Y 204 mean?
The boiler is waiting. The measured flow temperature is higher than the calculated or set heating water temperature.
How do I fix fault code 0Y 204 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 0Y 204?
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 0Y 204 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 →