BoilerFaultCodesPotterton A09-12 Fault Code
Also written as A0912 — same fault.
The Potterton A09-12 fault code means: your boiler's main internal computer has developed a serious communication fault and can no longer control the heating process safely.. It appears on 1 Potterton model in our database.
Technical description: Internal boiler control failure
What causes the Potterton A09-12 fault?
This fault occurs when the boiler's central control board suffers an internal electronic failure, meaning it can no longer send or receive signals from the sensors and gas valve. It is typically caused by aged electrical components on the circuit board wearing out or developing a short circuit over time. In some cases, a loose or damaged wiring connection between the board and the main internal components can also trigger this communication breakdown.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Potterton models that show the A09-12 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton A09-12 fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026