DHW NTC probe temperature reading (if installed) °C / °F
The P04 error code on Immergas boilers indicates dhw ntc probe temperature reading (if installed) °c / °f.
Immergas P04 means: dhw ntc probe temperature reading (if installed) °c / °f. The usual causes are riscaldamento (anti, cycle ch) or tis is used to set a waiting time to avoid the boiler from switching on multiple. You can safely reset the boiler once — if P04 returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does P04 Mean
The P04 code is shown by the boiler’s control board when it detects dhw ntc probe temperature reading (if installed) °c / °f. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| The display shows P04 and the boiler stops until the fault is cleared |
Common Causes
Causes documented in 1 technical sources.
| Cause |
|---|
| riscaldamento (Anti |
| cycle CH) |
| Tis is used to set a waiting time to avoid the boiler from switching on multiple |
| times and frequently during CH mode |
| 0 ÷ 15 minutes |
| 3 minutes |
Safety Warning
P04 involves electrical or pressure-related components. Do not attempt repairs without proper qualifications. Ensure the boiler is electrically isolated before any inspection. If you notice water leaks, unusual sounds, or pressure anomalies, contact a qualified heating engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
Open a hot water tap and check if the boiler fires — if not, check the flow sensor/turbine
Check the diverter valve — with a hot water tap open, feel the central heating flow pipe
if it is hot, the diverter is not switching
Check the DHW NTC sensor — measure resistance and compare with manufacturer's chart
Check the plate heat exchanger — if the boiler fires but water is lukewarm, the PHE may be scaled
Verify the DHW temperature setting on the boiler controls
How to Fix It
Replace the fan motor assembly if bearings are worn or motor is not running
replace the air pressure switch if it is stuck or reading incorrectly
clear any flue or condensate blockage
repair or replace damaged wiring
if PCB is not providing the signal, replace the PCB
Refer to the Immergas service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
Diagnostic Tools
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Affected Models
Immergas models that can display fault code P04:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Immergas models | — | Possible |
Frequently Asked Questions
Replace the fan motor assembly if bearings are worn or motor is not running. According to the technical documentation, this is the first check on the list for P04.
P04 is not classified as a high-severity fault, so the boiler can be reset once. If P04 comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.