How much does it cost to fix Biasi error code Main circuit pressure - yellow?

Typical repair cost for the Biasi Main circuit pressure - yellow fault is £0-120 including labour.

Main circuit pressure - yellow High

Biasi Main circuit pressure - yellow Fault Code

Q: What does the Biasi Main circuit pressure - yellow fault code mean?

Your boiler has detected that the water pressure is too low, which prevents it from heating up safely.

Also written as MAINCIRCUITPRESSUREYELLOW — same fault.

The Biasi Main circuit pressure - yellow fault code means: your boiler has detected that the water pressure is too low, which prevents it from heating up safely.. It appears on 1 Biasi model in our database.

Technical description: Pressure is too low (approx. below 1 bar)

Typical repair cost £0-120 (including labour)

DIY fix possible

Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Slowly open the small valves on the filling loop until you hear water moving.Watch the pressure gauge and close the valves once the needle reaches between 1 and 1.5 bar.

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Biasi models that show the Main circuit pressure - yellow fault code

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

Gaia Repair: £0-120

Source

Biasi Main circuit pressure - yellow 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