How much does it cost to fix Viessmann error code 02?

Typical repair cost for the Viessmann 02 fault is £120-£350 including labour.

02 High

Viessmann 02 Fault Code

Q: What does the Viessmann 02 fault code mean?

Your boiler has shut itself down as a safety precaution because it has detected an overheating issue within the system.

The Viessmann 02 fault code means: your boiler has shut itself down as a safety precaution because it has detected an overheating issue within the system.. It appears on 12 Viessmann models in our database.

Technical description: Burner control switches to lockout

What causes the Viessmann 02 fault?

This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to cut the power to the burner. The most common reasons include a failing pump that isn't moving water away from the burner quickly enough, or a buildup of debris and sludge that is restricting flow through the heat exchanger.

This issue often surfaces during the first cold spell of autumn when the heating is turned back on after sitting idle all summer, which can cause internal pump components to seize.

Typical repair cost £120-£350 (including labour)

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 02 fault code

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

Source

Viessmann 02 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