BoilerFaultCodesVokera E03 Fault Code
The Vokera E03 fault code means: your boiler's internal computer has developed a fault and can no longer talk to the rest of the system.. It appears on 6 Vokera models in our database.
Technical description: Flue gas thermostat fault or fan fault
What causes the Vokera E03 fault?
This fault occurs when the boiler's main control board suffers an internal electronic failure or a loss of communication with its connected sensors. It is usually caused by aging electrical components on the circuit board wearing out or, in some cases, a loose connection in the internal wiring harness. Because the 'brain' of the boiler can no longer process safety data, it shuts down the system entirely to prevent accidents.
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 E03 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera E03 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