A01.23 High

Remeha A01.23 Fault Code

Also written as A0123 — same fault.

The Remeha A01.23 fault code means: your boiler has detected that the fuel and air mixture used to heat your home is not burning correctly, so it has safely shut itself down to prevent unsafe operation.. It appears on 1 Remeha model 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: Poor Combustion: Poor combustion
Typical repair cost £150-350 (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 A01.23 fault code

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

Source

Remeha A01.23 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 7 July 2026