Medium
E83-121 on Biasi Riva Compact 24S (M90E.24S)

Your boiler is detecting an issue with the internal expansion vessel, which regulates system pressure and protects your heating pipes from bursting.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Expansionvessel

Shared across the Riva range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

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

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Related fault codes

E02View →E34View →

All 24 fault codes on the Riva Compact 24S (M90E.24S)

Seeing a different code? Every code this model can display, in one place.

164-026169-083E00-684E00-688E01E01-204E01-205E83-013E83-082E83-086E83-101E83-122E83-126E83-127E83-129E83-142E83-145E83-178E83-180E83-181E83-196E83-197N/A

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