BoilerFaultCodesVokera E33 Fault Code
The Vokera E33 fault code means: your boiler has detected an electrical issue with its power supply or wiring, meaning it cannot safely start the burner.. It appears on 2 Vokera models in our database.
Technical description: Phase error
What causes the Vokera E33 fault?
This fault occurs when the boiler detects an inconsistency with the electrical supply, specifically that the live and neutral wires may be swapped or there is a lack of a solid earth connection. The most common reason is a recent electrical repair in the home or a faulty internal component that has disrupted the correct flow of electricity. Because the boiler requires a specific electrical polarity to safely detect a flame, it prevents the burner from firing until the wiring is corrected.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Search the official register for a qualified engineer in your area.
Gas Safe Register →Vokera models that show the E33 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera E33 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