BoilerFaultCodesViessmann 0A Fault Code
The Viessmann 0A fault code means: your boiler has detected an issue with the gas pressure or a component failure and has shut down as a safety precaution.. It appears on 3 Viessmann models in our database.
Technical description: Burner control switches to lockout
What causes the Viessmann 0A fault?
This fault occurs when the boiler's internal safety sensors detect that the gas pressure is either too low or fluctuating, preventing the burner from staying lit. It is often caused by a failing gas valve that can't regulate the flow properly or worn ignition electrodes that are struggling to spark. In some cases, the main control board has developed a communication error and can no longer safely manage the combustion process.
This fault can be more frequent during extreme cold snaps when high local demand for gas can cause drops in mains pressure, or when debris in the gas line settles during the first heavy use of the winter.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Viessmann models that show the 0A fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann 0A fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.
- Viessmann Vitodens 111-W manual (PDF)
- Viessmann Vitodens 222-F manual (PDF)
- Viessmann Vitopend 100 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026