A 12 High

Vokera A 12 Fault Code

Also written as A12 — same fault.

The Vokera A 12 fault code means: your boiler's computer memory has become corrupted, preventing the internal software from starting up correctly.. It appears on 1 Vokera 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: The values of the E2PROM do not match those of the main software. Replace the circuit board.
Typical repair cost £300-500 (including labour)

Engineer required

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

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Vokera models that show the A 12 fault code

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

Source

Vokera A 12 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026