03 High

Vokera 03 Fault Code

The Vokera 03 fault code means: your boiler has detected a problem safely clearing waste gases through the flue pipe, which has caused the system to shut down for safety.. It appears on 13 Vokera models 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: Problem with fan/flue. Re-set as described for code 01.

What causes the Vokera 03 fault?

This fault occurs when the boiler's internal safety sensors detect that the fan isn't moving enough air to safely expel exhaust gases through the flue. The most common reasons are a failing fan motor, a blockage in the flue pipe, or a build-up of debris in the small plastic tubes that monitor air pressure. Because the boiler cannot guarantee that harmful fumes are being moved outside, it shuts down as a critical safety precaution.

This fault can be more frequent during periods of heavy wind or extreme cold, as high gusts can disrupt the air pressure balance and ice can block the flue terminal.

Typical repair cost £150-350 (including labour)

DIY fix possible

Locate the mode selector switch on the front control panel.Move the switch to the 'OFF/RESET' position and wait for approximately 10 seconds.Move the switch back to either the 'Hot Water Only' or 'Heating and Hot Water' position to attempt a restart.

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Vokera models that show the 03 fault code

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

Source

Vokera 03 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 27 April 2026