BoilerFaultCodesBiasi 18E Fault Code
The Biasi 18E fault code means: your boiler has detected that there is not enough water circulating inside the system to operate safely.. It appears on 1 Biasi model in our database.
Technical description: Faulty primary circuit (no water or absence of flow)
DIY fix possible
Check the boiler pressure gauge on the front display; if it is below 1 bar, your system needs re-pressurizing.Locate the external filling loop (usually two silver taps connected by a flexible hose underneath the boiler).Slowly open the taps to allow water into the system until the gauge reaches 1.5 bar, then turn both taps off tightly.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like 18E: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Biasi models that show the 18E fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Biasi 18E 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