Er04+ High

Biasi Er04+ Fault Code

Also written as ER04 — same fault.

The Biasi Er04+ fault code means: your boiler has detected that there is not enough water pressure or the water isn't moving through the system properly to operate safely.. It appears on 1 Biasi model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Faulty primary circuit (nowater or absence of flow)
Typical repair cost £100-£280 (including labour)

DIY fix possible

Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.If the pressure is too low, use the filling loop valves underneath the boiler to top it up.Ensure all radiator valves and isolation valves are fully open.Restart the boiler using the reset button once the pressure is corrected.

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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 27 April 2026