How much does it cost to fix Biasi error code E18?

Typical repair cost for the Biasi E18 fault is £90-180 including labour.

E18 High

Biasi E18 Fault Code

Q: What does the Biasi E18 fault code mean?

Your boiler has detected that the water returning from your radiators is getting too hot, which often points to a circulation problem or a faulty sensor.

The Biasi E18 fault code means: your boiler has detected that the water returning from your radiators is getting too hot, which often points to a circulation problem or a faulty sensor.. It appears on 3 Biasi models in our database.

Technical description: Heating return NTC probe overtemperature

Typical repair cost £90-180 (including labour)

DIY fix possible

Check that all radiator valves (TRVs) are fully openEnsure the boiler pressure gauge is between 1.0 and 1.5 barBleed all radiators to remove trapped airReset the boiler to see if the fault clears

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Biasi models that show the E18 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Biasi E18 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