How much does it cost to fix Viessmann error code A0:2?

Typical repair cost for the Viessmann A0:2 fault is £90-250 including labour.

A0:2 Medium

Viessmann A0:2 Fault Code

Q: What does the Viessmann A0:2 fault code mean?

Your boiler has lost communication with your wall-mounted remote control unit, meaning the thermostat cannot talk to the boiler to manage your heating.

Also written as A02 — same fault.

The Viessmann A0:2 fault code means: your boiler has lost communication with your wall-mounted remote control unit, meaning the thermostat cannot talk to the boiler to manage your heating.. It appears on 5 Viessmann models in our database.

Technical description: With Vitotrol 300 (automatic recognition)

What causes the Viessmann A0:2 fault?

This fault occurs when the boiler loses its digital handshake with the Vitotrol room controller, meaning they can no longer exchange temperature data. The most common reason is a temporary glitch in the communication bus or a loose connection in the low-voltage wiring between the two units. In some cases, it can also be caused by electrical interference or a failing internal communication module.

Typical repair cost £90-250 (including labour)

DIY fix possible

Check that the Vitotrol unit is fully clipped into its wall baseInspect the wiring between the control and the boiler for any obvious loose connections if accessibleTurn the boiler power off and back on at the fused spur to attempt a communication reset

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Viessmann models that show the A0:2 fault code

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

Source

Viessmann A0:2 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.

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