BoilerFaultCodesBiasi Er04+ Fault Code
Also written as ER04 — same fault.
The Biasi Er04+ fault code means: your boiler has detected that there is either not enough water inside the system or that the water is not circulating correctly, which prevents it from heating your home.. It appears on 3 Biasi models in our database.
Technical description: Faulty primary circuit (no water or absence of flow)
DIY fix possible
Check your boiler pressure gauge; if it is below 1 bar, locate the filling loop under the boiler.Open the valves to allow water into the system until the gauge reaches 1.5 bar, then turn the valves off securely.Restart your boiler to see if the error clears.
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Biasi models that show the Er04+ fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Biasi Er04+ fault code information on this page is sourced and cross-checked against the official Biasi service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026