How much does it cost to fix Biasi error code E83---121?

Typical repair cost for the Biasi E83---121 fault is £120-250 including labour.

E83---121 High

Biasi E83---121 Fault Code

Q: What does the Biasi E83---121 fault code mean?

Your boiler is struggling to manage the internal pressure changes as the water heats up, which is causing the system to shut down.

Also written as E83121 — same fault.

The Biasi E83---121 fault code means: your boiler is struggling to manage the internal pressure changes as the water heats up, which is causing the system to shut down.. It appears on 1 Biasi model in our database.

Technical description: Expansion vessel

Typical repair cost £120-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Biasi models that show the E83---121 fault code

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

Riva Compact 24S Repair: £120-250

Source

Biasi E83---121 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