b43 High

Remeha b43 Fault Code

Also written as B43 — same fault.

The Remeha b43 fault code means: the internal computer settings for your boiler have been altered, causing the system to stop working because it no longer knows how to run safely.. It appears on 2 Remeha models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: One or several adjusted parameters out of range including some factory defaults which should not have been changed.
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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Remeha models that show the b43 fault code

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

Source

Remeha b43 fault code information on this page is sourced and cross-checked against the official Remeha service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026